This manual documents the Eplain macros for TeX (version 2.8.4, Sept 2004). Eplain provides functionality that is intended to be useful regardless of how your document is actually formatted.
Copyright (C) 1989, 90, 91, 92, 93, 94, 97, 2004 Karl Berry. Steven Smith wrote the documentation for the commutative diagram macros. (He also wrote the macros.) Some additions/corrections by Adam Lewenberg.
Permission is granted to make and distribute verbatim copies of this manual provided the copyright notice and this permission notice are preserved on all copies.
Permission is granted to copy and distribute modified versions of this manual under the conditions for verbatim copying, provided also that the section entitled “GNU General Public License” is included exactly as in the original, and provided that the entire resulting derived work is distributed under the terms of a permission notice identical to this one.
Permission is granted to copy and distribute translations of this manual into another language, under the above conditions for modified versions, except that the section entitled “GNU General Public License” may be included in a translation approved by the author instead of in the original English.
--- The Detailed Node Listing ---
User definitions
Citations
Displays
Lists
Cross-references
Page references
Equation references
Arrow theoretic diagrams
Commutative diagrams
Programming definitions
Expansion
The Eplain macro package expands on and extends the definitions in plain TeX. This manual describes the definitions that you, as either an author or a macro writer, might like to use. It doesn't discuss the implementation; see comments in the source code (xeplain.tex) for that.
Eplain is not intended to provide “generic” typesetting capabilities, as do LaTeX (written by Leslie Lamport) or Texinfo (written by Richard Stallman and others). Instead, it provides definitions that are intended to be useful regardless of the high-level commands that you use when you actually prepare your manuscript.
For example, Eplain does not have a command \section, which
would format section headings in an “appropriate” way, such as
LaTeX's \section. The philosophy of Eplain is
that some people will always need or want to go beyond the macro
designer's idea of “appropriate”. Such canned macros are
fine—as long as you are willing to accept the resulting output. If
you don't like the results, or if you are trying to match a different
format, you are out of luck.
On the other hand, almost everyone would like capabilities such as cross-referencing by labels, so that you don't have to put actual page numbers in the manuscript. The author of Eplain is not aware of any generally available macro packages that (1) do not force their typographic style on an author, and yet (2) provide such capabilities.
Besides such generic macros as cross-referencing, Eplain contains another set of definitions: ones that change the conventions of plain TeX's output. For example, math displays in TeX are, by default, centered. If you want your displays to come out left-justified, you have to plow through The TeXbook to find some way to do it, and then adapt the code to your own needs. Eplain tries to take care of the messy details of such things, while still leaving the detailed appearance of the output up to you.
Finally, numerous definitions turned out to be useful as Eplain was developed. They are also documented in this manual, on the chance that people writing other macros will be able to use them.
You can send bug reports or suggestions to tex-eplain@cs.umb.edu. The
current version number of Eplain is defined as the macro
\fmtversion
at the end of the source file eplain.tex. When corresponding,
please refer to it.
To get on this mailing list yourself, email tex-eplain-request@cs.umb.edu with a message whose body contains a line
subscribe you@your.preferred.address
The simplest way to install Eplain is simply to install the file eplain.tex in a directory where TeX will find it. What that directory is obviously depends on your operating system and TeX installation. I personally install eplain.tex in a directory /usr/local/lib/texmf/tex/plain.
If you want, you can also create a format (.fmt)
file for Eplain, which will eliminate the time spent reading the macro
source file with \input. You do this by issuing a sequence of
Unix commands something like this:
prompt$ touch eplain.aux
prompt$ initex
This is TeX, ...
**&plain eplain
(eplain.tex)
*\dump
... messages ...
You must make sure that eplain.aux exists before you run initex; otherwise, warning messages about undefined labels will never be issued.
You then have to install the resulting eplain.fmt in some system
directory or set an environment variable to tell TeX how to find it.
I install the format files in /usr/local/lib/texmf/ini; the
environment variable for the Web2C port of TeX to Unix is
TEXFORMATS.
Some implementations of TeX (including Web2C) use the name by which TeX is invoked to determine what format to read. For them, you should make a link to the virtex program named etex, and then install the format file with the name etex.fmt. This lets users invoke TeX as etex and get the format file read automatically, without having to say &eplain.
For convenience, the file etex.tex in the distribution directory
does \input eplain and then \dump, so that if you replace
eplain with etex in the example above, the format file
will end up with the right name.
The install target in the Makefile does all this properly
for Unix systems and Web2C. You may have to change the pathnames.
Under emtex, eaj@acpub.duke.edu says that
tex386 -i ^&plain eplain \dump
produces a format file.
The simplest way to use Eplain is simply to put:
\input eplain
at the beginning of your input file. The macro file is small enough that reading it does not take an unbearably long time—at least on contemporary machines.
In addition, if a format (.fmt)
file has been created for Eplain (see the previous section), you can
eliminate the time spent reading the macro source file. You do this by
responding &eplain or &etex to TeX's ** prompt.
For example:
initex
This is TeX, ...
**&eplain myfile
Depending on the implementation of TeX which you are using, you might also be able to invoke TeX as etex and have the format file automatically read.
If you write something which you will be distributing to others, you
won't know if the Eplain format will be loaded already. If it is, then
doing \input eplain will waste time; if it isn't, then you must
load it. To solve this, Eplain defines the control sequence
\eplain
to be the letter t (a convention borrowed from Lisp; it doesn't
actually matter what the definition is, only that the definition
exists). Therefore, you can do the following:
\ifx\eplain\undefined \input eplain \fi
where \undefined must never acquire a definition.
Eplain consists of several source files:
The file eplain.tex is all of these files merged together, with comments removed.
All of these files except xeplain.tex can be input individually, if all you want are the definitions in that file.
Also, since the bibliography macros are fairly extensive, you might not
want to load them, to conserve TeX's memory. Therefore, if the
control sequence \nobibtex
is defined, then the bibliography definitions are skipped. You must set
\nobibtex before eplain.tex is read, naturally. For
example, you could start your input file like this:
\let\nobibtex = t
\input eplain
By default, \nobibtex is undefined, and so the bibliography
definitions are made.
Likewise, define \noarrow if you don't want to include the
commutative diagram macros from arrow.tex, perhaps because you
already have conflicting ones.
If you don't want to read or write an aux file at all, for any
kind of cross-referencing, define \noauxfile
before reading eplain.tex. This also turns off all warnings
about undefined labels.
Eplain conflicts with AMSTeX (more precisely, with amsppt.sty)
The macros \cite and \ref are defined by both.
If you want to use AMSTeX's \cite, the solution is to define
\nobibtex before reading Eplain, as described above.
If you have amsppt.sty loaded and use \ref, Eplain writes
a warning on your terminal. If you want to use the AMSTeX
\ref, do \let\ref = \amsref after reading Eplain.
To avoid the warning, do \let\ref = \eplainref after reading
Eplain and before using \ref.
This chapter describes definitions that are meant to be used directly in a document. When appropriate, ways to change the default formatting are described in subsections.
Plain TeX provides the \tracingall command, to turn on the
maximum amount of tracing possible in TeX. The (usually voluminous)
output from \tracingall goes both on the terminal and into the
transcript file.
It is sometimes easier to have the output go only to the transcript
file, so you can peruse it at your leisure and not obscure other output
to the terminal. So, Eplain provides the command \loggingall.
(For some reason, this command is available in Metafont, but not in
TeX.)
It is also sometimes useful to see the complete contents of boxes.
\tracingboxes does this. (It doesn't affect whether or not the
contents
are shown on the terminal.)
You can turn off all tracing with \tracingoff.
You can also turn logging on and off globally, so you don't have to
worry about whether or not you're inside a group at the time of command.
These variants are named \gloggingall
and \gtracingall.
Finally, if you write your own help messages (see \newhelp
in The TeXbook), you want a convenient way to break lines in
them. This is what TeX's \newlinechar parameter is for;
however, plain TeX doesn't set \newlinechar. Therefore,
Eplain defines it to be the character ^^J.
For example, one of Eplain's own error messages is defined as follows:
\newhelp\envhelp{Perhaps you forgot to end the previous^^J%
environment? I'm finishing off the current group,^^J%
hoping that will fix it.}%
The default dimensions of rules are defined in chapter 21 of the
The TeXbook. To sum up what is given there, the “thickness”
of rules is
0.4pt by default. Eplain defines three parameters that let you change
this dimension: \hruledefaultheight, \hruledefaultdepth,
and \vruledefaultwidth. By default, they are defined as
The TeXbook describes.
But it would be wrong to redefine \hrule and \vrule. For
one thing, some macros in plain TeX depend on the default dimensions
being used; for another, rules are used quite heavily, and the
performance impact of making it a macro can be noticeable. Therefore,
to take advantage of the default rule parameters, you must use
\ehrule
and \evrule.
Bibliographies are part of almost every technical document. To handle them easily, you need two things: a program to do the tedious formatting, and a way to cite references by labels, rather than by numbers. The BibTeX program, written by Oren Patashnik, takes care of the first item; the citation commands in LaTeX, written to be used with BibTeX, take care of the second. Therefore, Eplain adopts the use of BibTeX, and virtually the same interface as LaTeX.
The general idea is that you put citation commands in the text of your document, and commands saying where the bibliography data is. When you run TeX, these commands produce output on the file with the same root name as your document (by default) and the extension .aux. BibTeX reads this file. You should put the bibliography data in a file or files with the extension .bib. BibTeX writes out a file with the same root name as your document and extension .bbl. Eplain reads this file the next time you run your document through TeX. (It takes multiple passes to get everything straight, because usually after seeing your bibliography typeset, you want to make changes in the .bib file, which means you have to run BibTeX again, which means you have to run TeX again...) An annotated example of the whole process is given below.
If your document has more than one bibliography—for example, if it
is a collection of papers—you can tell Eplain to use a different root
name for the .bbl file by defining the control sequence
\bblfilebasename.
The default definition is simply \jobname.
See the document BibTeXing (whose text is in the file btxdoc.tex, which should be in the Eplain distribution you got) for information on how to write your .bib files. Both the BibTeX and the Eplain distributions contain several examples, also.
The \cite
command produces a citation in the text of your document. The exact
printed form the citation will take is under your control;
see Formatting citations. \cite takes one
required argument, a comma-separated list of cross-reference labels
(see Cross-references, for exactly what characters are allowed in
such labels). Warning: spaces in this list are taken as part of the
following label name, which is probably not what you expect.
The \cite command also produces a command
in the .aux file that tells BibTeX to retrieve the given reference(s)
from the .bib file. \cite also takes one optional argument,
which you specify within square brackets, as in LaTeX. This text is
simply typeset after the citations. (See the example below.)
Another command, \nocite,
puts the given reference(s) into the bibliography, but produces nothing
in the text.
The \bibliography
command is next. It serves two purposes: producing the typeset
bibliography, and telling BibTeX the root names of the .bib
files. Therefore, the argument to \bibliography is a comma
separated list of the .bib files (without the .bib). Again,
spaces in this list are significant.
You tell BibTeX the particular style in which you want your
bibliography typeset with one more command:
\bibliographystyle.
The argument to this is a single filename style, which tells
BibTeX to look for a file style.bst.
See the document Designing BibTeX styles (whose text is in the
btxhak.tex) for information on how to write your own styles.
Eplain automatically reads the citations from the .aux file when your job starts.
If you don't want to see the messages about undefined citations, you
can say \xrefwarningfalse before making any citations.
Eplain automatically does this if the .aux file does not exist.
You can restore the default by saying \xrefwarningtrue.
Here is a TeX input file that illustrates the various commands.
\input eplain % Reads the .aux file.
Two citations to Knuthian works:
\cite[note]{surreal,concrete-math}.
\beginsection{References.}\par % Title for the bibliography.
\bibliography{knuth} % Use knuth.bib for the labels.
\bibliographystyle{plain} % Number the references.
\end % End of the document.
If we suppose that this file was named citex.tex and that the
bibliography data is in knuth.bib (as the \bibliography
command says), the following commands do what's required. ($
represents the shell prompt.)
$ tex citex (produces undefined citation messages)
$ bibtex citex (read knuth.bib and citex.aux, write citex.bbl)
$ tex citex (read citex.bbl, still have undefined citations)
$ tex citex (one more time, to resolve the references)
The output looks something like (because we used the plain bibliography style):
Two citations to Knuthian works: [2,1 note].References
[1] Ronald L. Graham, Donald E. Knuth, and Oren Patashnik. Concrete Mathematics. Addison-Wesley, Reading, Massachusetts, 1989.
[2] Donald E. Knuth. Surreal Numbers. Addison-Wesley, Reading, Massachusetts, 1974.
See the BibTeX documentation for information on how to write the
bibliography databases, and the bibliography styles that are available.
(If you want your references printed with names, as in [Knu74], instead
of numbered, the bibliography style is alpha.)
You may wish to change Eplain's formatting of citations; i.e., the
result of your \cite commands. By default, the citation labels
are printed one after another, separated by commas and enclosed in
brackets, using the main text font. Some formats require other styles,
such as superscripted labels. You can accomodate such formats by
redefining the following macros.
\printcitestart\printcitefinish\cite command. By default, they produce a
[ and ], respectively.
\printbetweencitations\cite command has multiple citations, as in
\cite{acp,texbook}, Eplain expands this macro in between each
pair of citations. By default, it produces a comma followed by a space.
\printcitenote\cite command. If the \cite command had no note, this
macro isn't used. Otherwise, it should print the note. By default, the
note is preceded with a comma and a space.
Here is an example, showing you could produce citations as superscripted labels, with the optional notes in parentheses.
\def\printcitestart{\unskip $^\bgroup}
\def\printbetweencitations{,}
\def\printcitefinish{\egroup$}
\def\printcitenote#1{\hbox{\sevenrm\space (#1)}}
You may wish to change Eplain's formatting of the bibliography, especially with respect to the fonts that are used. Therefore, Eplain provides the following control sequences:
\biblabelwidth\dimen register, and its value
is the width of the widest label in the bibliography. Although it is
unlikely you will ever want to redefine it, you might want
to use it if you redefine \biblabelprint, below.
\biblabelprint\biblabelwidth, and is followed by
an enspace. When you want to change the spacing around the labels, this
is the right macro to redefine.
\biblabelcontents\bblrm (below), and enclosed in
brackets. When you want to change the appearance of the label, but not
the spacing around it, this is the right macro to redefine.
\bblrm\bblem\bblsc\bblnewblock\biblabelextraspace\biblabelwidth plus this. The default is .5em, where the
em width is taken from the \bblrm font. If you want to change
this, you should do it inside \bblhook.
\bblhook\bblhook:
\parskip, which produces extra space between the items; and
\biblabelextraspace, which is described above.
(By the way, \hookappend won't work with \bblhook, despite
the names. Just use \def.)
If you are really desperate, you can also hand-edit the .bbl file that BibTeX produces to do anything you wish.
By default, TeX centers displayed material. (Displayed material is
just whatever you put between $$'s—it's not necessarily
mathematics.) Many layouts would be better served if the displayed
material was left-justified. Therefore, Eplain provides the command
\leftdisplays,
which indents displayed material by \parindent plus
\leftskip, plus \leftdisplayindent.
You can go back to centering displays with \centereddisplays.
(It is usually poor typography to have both centered and left-justified
displays in a single publication, though.)
\leftdisplays also changes the plain TeX commands that deal
with alignments inside math displays,
\displaylines,
\eqalignno,
and \leqalignno,
to produce left-justified text. You can still override this formatting
by inserting \hfill glue, as explained in The TeXbook.
If you want some other kind of formatting, you can write a definition
of your own, analogous to \leftdisplays. You need only make sure
that \leftdisplaysetup
is called at the beginning of every display (presumably by invoking it
in TeX's \everydisplay parameter), and to define
\generaldisplay.
\leftdisplays expands the old value of \everydisplay
before calling \leftdisplaysetup, so that any changes you have made
to it won't be lost. That old token list as available as the value of
the token register \previouseverydisplay.
TeX provides the day, month, and year as numeric quantities (unless your TeX implementation is woefully deficient). Eplain provides some control sequences to make them a little more friendly to humans.
\monthname
produces the name of the current month, abbreviated to three letters.
\fullmonthname
produces the name of the current month, unabbreviated (in English).
\timestring
produces the current time, as in `1:14 p.m.'
\timestamp
produces the current date and time, as in `23 Apr 64 1:14 p.m.'.
(Except the spacing is slightly different.)
\today
produces the current date, as in `23 April 1964'.
Many documents require lists of items, either numbered or simply
enumerated. Plain TeX defines one macro to help with creating lists,
\item, but that is insufficient in many cases. Therefore,
Eplain provides two pairs of commands:
\numberedlist ... \endnumberedlist\orderedlist ... \endorderedlist\numberedlist
labels the items with lowercase letters, starting with `a'. Another
nested \numberedlist labels the items with roman numerals. Yet
more deeply nested numbered lists label items with *.
\unorderedlist ... \endunorderedlist\unorderedlist labels items with
em-dashes. Doubly (and deeper) nested unordered lists label items with
`*'s.
The two kinds of lists can be nested within each other, as well.
In both kinds of lists, you begin an item with \li.
An item may continue for several paragraphs. Each item starts a
paragraph.
You can give \li an optional argument, a cross-reference label.
It's defined to be the “marker” for the current item. This is useful
if the list items are numbered. You can produce the value of the label
with \xrefn. See Cross-references.
You can also say \listcompact
right after \numberedlist or \unorderedlist. The items in
the list will then not have any extra space between them
(see Formatting lists). You might want to do this if the items in
this particular list are short.
Here is an example:
\numberedlist\listcompact
\li The first item.
\li The second item.
The second paragraph of the second item.
\endnumberedlist
Several registers define the spacing associated with lists. It is likely that their default values won't suit your particular layout.
\abovelistskipamount, \belowlistskipamount\interitemskipamount\listcompact resets this to zero, as mentioned above.
\listleftindent, \listrightindent\listrightindent is the amount of space by which the list is
indented on the right; i.e., it is added to \rightskip.
\listleftindent is the amount of space, relative to
\parindent, by which the list is indented on the left. Why treat
the two parameters differently? Because (a) it is more useful to
make the list indentation depend on the paragraph indentation;
(b) footnotes aren't formatted right if \parindent is reset
to zero.
The three vertical glues are inserted by macros, and preceded by
penalties: \abovelistskip
does \vpenalty\abovelistpenalty
and then \vskip\abovelistskip. \belowlistskip
and \interitemskip
are analogous.
In addition, the macro \listmarkerspace
is called to separate the item label from the item text. This is set to
\enspace by default.
If you want to change the labels on the items, you can redefine these
macros:
\numberedmarker
or \unorderedmarker.
The following registers might be useful if you do:
\numberedlistdepth, \unorderedlistdepth\itemnumber, \itemletter\itemnumber starts at one, and \itemletter starts at 97,
i.e., lowercase `a'.
You can also redefine the control sequences that are used internally,
if you want to do something radically different: \beginlist
is invoked to begin both kinds of lists; \printitem
is invoked to print the label (and space following the label) for each
item; and \endlist
is invoked to end both kinds of
lists.
It is sometimes useful to include a file verbatim in your document;
for example, part of a computer program. The \listing
command is given one argument, a filename, and produces the contents of
that file in your document. \listing expands \listingfont
to set the current font. The default value of \listingfont
is \tt.
You can take arbitrary actions before reading the file by defining the macro
\setuplistinghook.
This is expanded just before the file is input.
If you want to have line numbers on the output, you can say
\let\setuplistinghook = \linenumberedlisting.
The line numbers are stored in the count register \lineno while
the file is being read. You can redefine the macro
\printlistinglineno to change how they are printed.
You can produce in-line verbatim text in your document with \verbatim.
End the text with |endverbatim. If you need a | in the text,
double it. If the first character of the verbatim text is a space, use
| . (| will work elsewhere in the argument, too, but
isn't necessary.)
For example:
\verbatim| ||\#%&!|endverbatim
produces |\#%&!.
Line breaks and spaces in the verbatim text are preserved.
You can change the verbatim escape character from the default |
with \verbatimescapechar char; for example, this changes
it to @.
\verbatimescapechar \@
The backslash is not necessary in some cases, but is in
others, depending on the catcode of the character. The argument to
\verbatimescapechar is used as \catcode `char, so
the exact rules follow that for \catcode.
Because \verbatim must change the category code of special
characters, calling inside a macro definition of your own does not work
properly. For example:
\def\mymacro{\verbatim &#%|endverbatim}% Doesn't work!
To accomplish this, you must change the category codes yourself before
making the macro definition. Perhaps \uncatcodespecials will
help you (see Category codes).
Producing a table of contents that is both useful and aesthetic is one of the most difficult design problems in any work. Naturally, Eplain does not pretend to solve the design problem. Collecting the raw data for a table of contents, however, is much the same across documents. Eplain uses an auxiliary file with extension .toc (and the same root name as your document) to save the information.
To write an entry for the table of contents, you say
\writetocentry{part}{text},
where part is the type of part this entry is, e.g.,
chapter, and text is the text of the title.
\writetocentry puts an entry into the .toc file that looks
like \tocpartentry{text}{page number}. The
text is written unexpanded.
A related command, \writenumberedtocentry, takes one additional
argument, the first token of which is expanded at the point of the
\writenumberedtocentry, but the rest of the argument is not
expanded. The usual application is when the parts of the document are
numbered. On the other hand, the one-level expansion allows you to use
the argument for other things as well (author's names in a proceedings,
say), and not have accents or other control sequences expanded. The
downside is that if you want full expansion of the third
argument, you don't get it—you must expand it yourself, before you
call \writenumberedtocentry.
For example:
\writenumberedtocentry{chapter}{A $\sin$ wave}{\the\chapno}
\writetocentry{section}{A section title}
Supposing \the\chapno expanded to 3 and that the
\write's occurred on pages eight and nine, respectively, the
above writes the following to the .toc file:
\tocchapterentry{A $\sin$ wave}{3}{8}
\tocsectionentry{A section title}{9}
You read the .toc file with the command \readtocfile.
Naturally, whatever \toc... entry commands that were written
to the file must be defined when \readtocfile is invoked. Eplain
has minimal definitions for \tocchapterentry,
\tocsectionentry, and \tocsubsectionentry, just to prevent
undefined control sequence errors in common cases. They aren't suitable
for anything but preliminary proofs.
After reading the .toc file, \readtocfile opens the file
for writing, thereby deleting the information from the previous run. You
should therefore arrange that \readtocfile be called
before the first call to a \writetoc... macro.
On the other hand, if you don't want to rewrite the .toc file,
perhaps because you are only running TeX on part of your manuscript,
you can set \rewritetocfilefalse.
By default, the .toc file has the root \jobname. If your
document has more than one contents—for example, if it is a collection
of papers, some of which have their own contents—you can tell Eplain
to use a different root name by defining the control sequence
\tocfilebasename.
In addition to the usual table of contents, you may want to have a list
of figures, list of tables, or other such contents-like list. You can do
this with \definecontentsfile{abbrev}. All of the
above commands are actually a special case that Eplain predefines with
\definecontentsfile{toc}
The abbrev is used both for the file extension and in the control sequence names.
It is often useful to refer the reader to other parts of your document; but putting literal page, section, equation, or whatever numbers in the text is certainly a bad thing.
Eplain therefore provides commands for symbolic cross-references. It uses an auxiliary file with extension .aux (and the same root name as your document) to keep track of the information. Therefore, it takes two passes to get the cross-references right—one to write them out, and one to read them in. Eplain automatically reads the .aux file at the first reference; after reading it, Eplain reopens it for writing.
You can control whether or not Eplain warns you about undefined labels. See Citations.
Labels in Eplain's cross-reference commands can use characters of category code eleven (letter), twelve (other), ten (space), three (math shift), four (alignment tab), seven (superscript), or eight (subscript). For example, (a1 $&^_ is a valid label (assuming the category codes of plain TeX), but %#\{ has no valid characters.
You can also do symbolic cross-references for bibliographic citations and list items. See Citations, and Lists.
Eplain provides the command \definexref for general
cross-references. It takes three arguments: the name of the label (see
section above for valid label names), the value of the label (which can
be anything), and the “class” of the reference—whether it's a
section, or theorem, or what. For example:
\definexref{sec-intro}{3.1}{section}
Of course, the label value is usually generated by another macro using TeX count registers or some such.
\definexref doesn't actually define label; instead, it
writes out the definition to the .aux file, where Eplain will read
it on the next TeX run.
The class argument is used by the \ref and \refs
commands. See the next section.
To retrieve the value of the label defined via \definexref (see
the previous section), Eplain provides the following macros:
\refn{label}\xrefn{label}\refn and \xrefn (they are synonyms) produce the bare
definition of label. If label isn't defined, issue a
warning, and produce label itself instead, in typewriter. (The
warning isn't given if \xrefwarningfalse.)
\ref{label}\definexref in the previous section), expand the control sequence
\c word (if it's defined) followed by a tie. Then call
\refn on label. (Example below.)
\refs{label}\ref, but append the letter s to the
\...word.
The purpose of the \...word macro is to produce the word
`Section' or `Figure' or whatever that usually precedes the actual
reference number.
Here is an example:
\def\sectionword{Section}
\definexref{sec-intro}{3.1}{section}
\definexref{sec-next}{3.2}{section}
See \refs{sec-intro} and \refn{sec-next} ...
This produces `See Sections 3.1 and 3.2 ...'
Eplain provides two commands for handling references to page numbers, one for definition and one for use.
\xrdef{label}\xref{label}Instead of referring to pages, it's most useful if equation labels
refer to equation numbers. Therefore, Eplain reserves a \count
register, \eqnumber,
for the current equation number, and increments it at each
numbered equation.
Here are the commands to define equation labels and then refer to them:
\eqdef{label}\eqnumber,
and, if the current context is not inner, then produces a \eqno
command. (The condition makes it possible to use \eqdef in an
\eqalignno construction, for example.) The text of the equation
number is produced using \eqprint. See Formatting equation references.
If label is empty, you still get an equation number (although
naturally you can't reliably refer to it). This is useful if you want
to put numbers on all equations in your document, and you don't want to
think up unique labels.
\eqdefn{label}\eqdef, except it always omits the \eqno
command. It can therefore be used in places where \eqdef can't;
for example, in a non-displayed equation. The text of the equation
number is not produced, so you can also use it in the (admittedly
unusual) circumstance when you want to define an equation label but not
print that label.
\eqref{label}\eqprint.
\eqrefn{label}\eqref, except it doesn't call \eqprint.
Equation labels can contain the same characters that are valid in general cross-references.
Both defining an equation label and referring to it should usually
produce output. This output is produced with the \eqprint macro,
which takes one argument, the equation number being defined or referred
to. By default, this just produces (number), where
number is the equation number. To produce the equation number in
a different font, or with different surrounding symbols, or whatever,
you can redefine \eqprint.
For example, the following definition would print all equation numbers
in italics. (The extra braces define a group, to keep the font change
from affecting surrounding text.)
\def\eqprint#1{{\it (#1)}}
In addition to changing the formatting of equation numbers, you might
to add more structure to the equation number; for example, you might
want to include the chapter number, to get equation numbers like
`(1.2)'. To achieve this, you redefine \eqconstruct.
For example:
\def\eqconstruct#1{\the\chapternumber.#1}
(If you are keeping the chapter number in a count register named
\chapternumber, naturally.)
The reason for having both \eqconstruct and \eqprint may
not be immediately apparent. The difference is that \eqconstruct
affects the text that cross-reference label is defined to be, while
\eqprint affects only what is typeset on the page. The example
just below might help.
Usually, you want equation labels to refer to equation numbers. But sometimes you might want a more complicated text. For example, you might have an equation `(1)', and then have a variation several pages later which you want to refer to as `(1*)'.
Therefore, Eplain allows you to give an optional argument (i.e., arbitrary text in square brackets) before the cross-reference label to \eqdef. Then, when you refer to the equation, that text is produced. Here's how to get the example just mentioned:
$$...\eqdef{a-eq}$$
...
$$...\eqdef[\eqrefn{a-eq}*]{a-eq-var}$$
In \eqref{a-eq-var}, we expand on \eqref{a-eq}, ...
We use \eqrefn in the cross-reference text, not
\eqref, so that \eqprint is called only once.
Eplain also provides for one level of substructure for equations. That is, you might want to define a related group of equations with numbers like `2.1' and `2.2', and then be able to refer to the group as a whole: “... in the system of equations (2)...”.
The commands to do this are \eqsubdef and
\eqsubdefn.
They take one label argument like their counterparts above,
and generally behave in the same way. The difference is in how they
construct the equation number: instead of using just \eqnumber,
they also use another counter, \subeqnumber.
This counter is advanced by one at every \eqsubdef or
\eqsubdefn, and reset to zero at every \eqdef or
\eqdefn.
You use \eqref to refer to subequations as well as main
equations.
To put the two together to construct the text that the label will
produce, they use a macro \eqsubreftext.
This macros takes two arguments, the “main” equation number (which,
because the equation label can be defined as arbitrary text, as
described in the previous section, might be anything at all) and the
“sub” equation number (which is always just a number). Eplain's
default definition just puts a period between them:
\def\eqsubreftext#1#2{#1.#2}%
You can redefine \eqsubreftext to print however you
like. For example, this definition makes the labels print as `2a',
`2b', and so on.
\newcount\subref
\def\eqsubreftext#1#2{%
\subref = #2 % The space stops a <number>.
\advance\subref by 96 % `a' is character code 97.
#1\char\subref
}
Sadly, we must define a new count register, \subref,
instead of using the scratch count register \count255, because
#1 might include other macro calls which use \count255.
Eplain provides support for generating raw material for an index, and for typesetting a sorted index. A separate program must do the actual collection and sorting of terms, because TeX itself has no support for sorting.
Eplain's indexing commands were designed to work with the program MakeIndex, available from ftp.math.utah.edu in the directory pub/tex/makeindex, and from CTAN hosts in tex-archive/indexing/makeindex; MakeIndex is also commonly included in prepackaged TeX distributions. It is beyond the scope of this manual to explain how to run MakeIndex, and all of its many options. See MAKEINDEX (MakeIndex).
The basic strategy for indexing works like this:
\idx; see the section `Indexing terms' below) write the raw index
material to foo.idx.
If your document needs more than one index, each must have its own
file. Therefore, Eplain provides the command \defineindex, which
takes an argument that is a single letter, which replaces i in
the filenames and in the indexing command names described below. For
example,
\defineindex{m}
defines the command \mdx to write to the file
foo.mdx. Eplain simply does \defineindex{i} to define
the default commands.
Indexing commands in Eplain come in pairs: one command that only writes the index entry to the .idx file (see above section), and one that also typesets the term being indexed. The former always starts with s (for “silent”). In either case, the name always includes Idx, where I is the index letter, also described above. Eplain defines the index i itself, so that's what we'll use in the names below.
The silent form of the commands take a subterm as a trailing optional
argument. For example, \sidx{truth}[definition of] on page 75
makes an index entry that will eventually be typeset (by default) as
truth
definition of, 75
Also, the silent commands ignore trailing spaces. The non-silent ones do not.
\sidx{term}[subterm] makes an index entry for
term, optionally with subterm subterm.
\idx{term} also produces term as output. Example:
\sidx{truth}[beauty of]
The beauty of truth is \idx{death}.
Subterms at the second and further levels can also be
specified in subterm, using the
\idxsubentryseparator character to separate
them. This character is by default !.
\sidxname{First M.}{von Last}[subterm]
makes an index
entry for von Last, First M.. You can change the
, by redefining \idxnameseparator.
\idxname{First M.}{von Last} also produces First M. von
Last as output. (These commands are useful special cases of \idx
and \sidx.) Example:
\sidxname{Richard}{Stark}
\idxname{Donald}{Westlake} has written many kinds of novels, under
almost as many names.
\sidxmarked\cs{term}[subterm] makes an index
entry for term[subterm], but term will be put
in the index as \cs{term}, but still sorted as just
term. \idxmarked\cs{term} also typesets
\cs{term}. This provides for the usual ways of changing
the typesetting of index entries. Example:
\def\article#1{``#1''}
\sidxmarked\article{Miss Elsa and Aunt Sophie}
Peter Drucker's \idxmarked\article{The Polanyis} is a remarkable
essay about a remarkable family.
\sidxsubmarked{term}\cs{subterm} makes an index
entry for term, subterm as usual, but also puts subterm in
the index as \cs{term}.
\idxsubmarked{term}\cs{subterm} also typesets
term \cs{subterm}, in the unlikely event that your
syntax is convoluted enough to make this useful. Example:
\def\title#1{{\sl #1}}
\sidxsubmarked{Anderson, Laurie}\title{Strange Angels}
The \idxsubmarked{Anderson}\title{Carmen} is a strange twist.
The commands above rely on MakeIndex's feature for separating sorting of
an index entry's from its typesetting. You can use this directly by
specifying an index entry as sort@typeset. For
example:
\sidx{Ap-weight@$A_\pi$-weight}
will sort as Ap-weight, but print with the proper math.
The @ here is MakeIndex's default character for this purpose.
See Style File-MakeIndex (MakeIndex). To make an index
entry with an @ in it, you have to escape it with a backslash;
Eplain provides no macros for doing this.
After any index command, Eplain runs
\hookaction{afterindexterm}. Because the index commands always
add a whatsit item to the current list, you may wish to preserve a
penalty or space past the new item. For example, given a conditional
\if@aftersctnhead set true when you're at a section heading, you
could do:
\hookaction{afterindexterm}{\if@aftersctnhead \nobreak \fi}
All the index commands described in the previous section take an initial optional argument before the index term, which modify the index entry's meaning in various ways. You can specify only one of the following in any given command.
These work via MakeIndex's “encapsulation” feature. See Customizing indexing, if you're not using the default characters for the MakeIndex operators. The other optional argument (specifying a subterm) is independent of these.
Here are the possibilities:
beginend \sidx[begin]{future}[Cohen, Leonard]
...
\sidx[end]{future}[Cohen, Leonard]
will typeset as something like
future,
Cohen, Leonard, 65–94
see \sidx[see]{analysis}[archetypal]{archetypal criticism}
becomes
analysis,
archetypal, See archetypal criticism
seealsosee (the previous item), but also allows for normal
index entries of the referencing term. Example:
\sidx[seealso]{archetypal criticism}[elements of]{dichotomies}
becomes
archetypal criticism,
elements of, 75, 97, 114, See also dichotomies
(Aside for the academically curious: The archetypally critical book I
took these dichotomous examples from is Laurence Berman's The
Musical Image, which I happened to co-design and typeset.)
pagemarkup=cs\cs before the page number in the typeset index,
thus allowing you to underline definitive entries, italicize examples,
and the like. You do not precede the control sequence cs
with a backslash. (That just leads to expansive difficulties.) Naturally
it is up to you to define the control sequences you want to use. Example:
\def\defn#1{{\sl #1}}
\sidx[pagemarkeup=defn]{indexing}
becomes something like
indexing, \defn{75}
As you are reading through a manuscript, it is helpful to see what terms have been indexed, so you can add others, catch miscellaneous errors, etc. (Speaking from bitter experience, I can say it is extremely error-prone to leave all indexing to the end of the writing, since it involves adding many TeX commands to the source files.)
So Eplain puts index terms in the margin of each page, if you
set \indexproofingtrue. It is false by default. The terms
are typeset by the macro \indexproofterm, which takes a single
argument, the term to be typeset. Eplain's definition of
\indexproofterm just puts it into an \hbox, first doing
\indexprooffont, which Eplain defines to select the font
cmtt8. With this definition long terms run off the page, but
since this is just for proofreading anyway, it seems acceptable.
On the other hand, we certainly don't want the index term to run into
the text of the page, so Eplain uses the right-hand side of the page
rather than the left-hand page (assuming a language read left to right
here). So \ifodd\pageno, Eplain kerns by \outsidemargin,
otherwise by \insidemargin. If those macros are undefined,
\indexsetmargins defines them to be one inch plus \hoffset.
To get the proofing index entries on the proper page, Eplain defines a new
insertion class \@indexproof. To unbox any index proofing
material, Eplain redefines \makeheadline to call
\indexproofunbox before the original \makeheadline. Thus,
if you have your own output routine, that redefines or doesn't use
\makeheadline, it's up to you to call \indexproofunbox at
the appropriate time.
The command \readindexfile{i} reads and typesets the
.ind file that MakeIndex outputs (from the .idx file which
the indexing commands in the previous sections write). Eplain defines a
number of commands that support the default MakeIndex output.
More precisely, \readindexfile reads
\indexfilebasename.index-letternd, where the
index-letter is the argument. \indexfilebasename is
\jobname by default, but if you have different indexes in
different parts of a book, you may wish to change it, just as with
bibliographies (see Citations).
MakeIndex was designed to work with LaTeX; therefore, by default the
.ind file starts with \begin{theindex} and ends with
\end{theindex}. If no \begin has been defined, Eplain
defines one to ignore its argument and set up for typesetting the index
(see below), and also defines a \end to ignore its argument. (In
a group, naturally, since there is a primitive \end).
Eplain calls \indexfonts, sets \parindent = 0pt, and does
\doublecolumns (see Multiple columns) at the
\begin{theindex}. \indexfonts does nothing by default;
it's just there for you to override. (Indexes are usually typeset in
smaller type than the main text.)
It ends the setup with \hookrun{beginindex}, so you can
override anything you like in that hook (see Hooks). For example:
\hookaction{beginindex}{\triplecolumns}
MakeIndex turns each main index entry into an \item, subentries
into \subitem, and subsubentries into \subsubitem. By
default, the first line of main entries are not indented, and subentries
are indented 1em per level. Main entries are preceded by a \vskip
of \aboveitemskipamount, 0pt plus2pt by default. Page
breaks are encouraged before main entries (\penalty -100), but
prohibited afterwards—Eplain has no provision for “continued”
index entries.
All levels do the following:
\hangindent = 1em
\raggedright
\hyphenpenalty = 10000
Each entry ends with \hookrun{indexitem}, so you can change any
of this. For example, to increase the allowable rag:
\hookaction{indexitem}{\advance\rightskip by 2em}
Finally, MakeIndex outputs \indexspace between each group of
entries in the .ind file. Eplain makes this equivalent to
\bigbreak.
By default, MakeIndex outputs , after each term in the index. To change this, you can add the following to your MakeIndex style (.ist) file:
delim_0 "\\afterindexterm "
delim_1 "\\afterindexterm "
delim_2 "\\afterindexterm "
Eplain makes \afterindexterm equivalent to
\quad.
You can also change the keywords Eplain recognizes (see Modifying index entries):
\idxrangebeginword\idxrangeendword\idxseecmdword\idxseealsocmdwordYou can also change the magic characters Eplain puts into the
.idx file, in case you've changed them in the .ist file:
\idxsubentryseparator\idxencapoperator\idxbeginrangemark\idxendrangemarkThere is no macro for the actual (@ by default)
character, because it's impossible to make it expand properly.
Finally, you can change the (imaginary) page number that “see also”
entries sort as by redefining \idxmaxpagenum. This is 99999 by
default, which is one digit too many for old versions of MakeIndex.
Eplain defines three commands to conveniently justify multiple
lines of text: \flushright, \flushleft, and
\center.
They all work in the same way; let's take \center as the
example. To start centering lines, you say \center inside a
group; to stop, you end the group. Between the two commands, each
end-of-line in the input file also starts a new line in the output file.
The entire block of text is broken into paragraphs at blank lines,
so all the TeX paragraph-shaping parameters apply in the usual way.
This is convenient, but it implies something else that isn't so
convenient: changes to any linespacing parameters, such as
\baselineskip, will have no effect on the paragraph in
which they are changed. TeX does not handle linespacing changes
within a paragraph (because it doesn't know where the line breaks are
until the end of the paragraph).
The space between paragraphs is by default one blank line's worth.
You can adjust this space by assigning to \blanklineskipamount;
this (vertical) glue is inserted after each blank line.
Here is an example:
{\center First line.
Second line, with a blank line before.
}
This produces:
You may wish to use the justification macros inside of your own macros. Just be sure to put them in a group. For example, here is how a title macro might be defined:
\def\title{\begingroup\titlefont\center}
\def\endtitle{\endgroup}
Eplain provides a single command, \makecolumns,
to make generating one particular kind of table easier. More ambitious
macro packages might be helpful to you for more difficult applications.
The files ruled.tex and TXSruled.tex, available from
lifshitz.ph.utexas.edu in texis/tables, is the only one I
know of.
Many tables are homogenous, i.e., all the entries are semantically the same. The arrangement into columns is to save space on the page, not to encode different meanings. In this kind of the table, it is useful to have the column breaks chosen automatically, so that you can add or delete entries without worrying about the column breaks.
\makecolumns takes two arguments: the number of entries in the
table, and the number of columns to break them into. As you can see
from the example below, the first argument is delimited by a slash, and
the second by a colon and a space (or end-of-line). The entries for the
table then follow, one per line (not including the line with the
\makecolumns command itself).
\parindent defines the space to the left of the
table. \hsize defines the width of the table.
So you can adjust the position of the table on the page by assignments
to these parameters, probably inside a group.
You can also control the penalty at a page break before the
\makecolumns by setting the parameter
\abovecolumnspenalty.
Usually, the table is preceded by some explanatory text. You wouldn't
want a page break to occur after the text and before the table, so
Eplain sets it to 10000. But if the table produced by
\makecolumns is standing on its own, \abovecolumnspenalty
should be decreased.
If you happen to give \makecolumns a smaller number of entries
than you really have, some text beyond the (intended) end of the table
will be incorporated into the table, probably producing an error
message, or at least some strange looking entries. And if you give
\makecolumns a larger number of entries than you really have,
some of the entries will be typeset as straight text, probably also
looking somewhat out of place.
Here is an example:
% Arrange 6 entries into 2 columns:
\makecolumns 6/2: % This line doesn't have an entry.
one
two
three
four
five
six
Text after the table.
This produces `one', `two', and `three' in the first column, and `four', `five', and `six' in the second.
TeX's primitives describe the type area in terms of an offset from the upper left corner, and the width and height of the type. Some people prefer to think in terms of the margins at the top, bottom, left, and right of the page, and most composition systems other than TeX conceive of the page laid out in this way. Therefore, Eplain provides commands to directly assign and increment the margins.
\topmargin = dimen\bottommargin = dimen\leftmargin = dimen\rightmargin = dimen= and the spaces around it are optional. The control
sequences here are not TeX registers, despite appearances;
therefore, commands like \showthe\topmargin will not do what you
expect.
\advancetopmargin by dimen\advancebottommargin by dimen\advanceleftmargin by dimen\advancerightmargin by dimenRegardless of whether you use the assignment or the advance commands,
Eplain always changes the type area in response, not the other margins.
For example, when TeX starts, the left and right margins are both one
inch. If you then say \leftmargin = 2in, the right margin will
remain at one inch, and the width of the lines (i.e., \hsize)
will decrease by one inch.
When you use any of these commands, Eplain computes the old value of the particular margin, by how much you want to change it, and then resets the values of TeX's primitive parameters to correspond. Unfortunately, Eplain cannot compute the right or bottom margin without help: you must tell it the full width and height of the final output page. It defines two new parameters for this:
\paperheight\paperwidthIf your output page has different dimensions than this, you must reassign to these parameters, as in
\paperheight = 11truein
\paperwidth = 17truein
Eplain provides for double, triple, and quadruple column output: say
\doublecolumns,
\triplecolumns,
or \quadcolumns,
and from that point on, the manuscript will be
set in columns. To go back to one column, say
\singlecolumn.
You may need to invoke \singlecolumn to balance the columns
on the last page of output.
To do a “column eject”, i.e., move to the top of the next column, do
\columnfill. This does not actually force an eject, however: it
merely inserts a kern of size \@normalvsize minus
\pagetotal (\@normalvsize being the usual height of the
page; to implement multicolumns, Eplain multiplies \vsize itself
by the number of columns). In most circumstances, a column break will be
forced after this kern (during the column splitting operation when the
whole page is output), as desired.
The columns are separated by the value of the dimen parameter
\gutter. Default value is two picas.
If you want to add vertical material between the columns, use
\gutterbox. For example, to put a vertical line between columns,
define
\gutterbox as
\def\gutterbox{\vbox to \dimen0{\vfil\hbox{\vrule height\dimen0}\vfil}}%
The dimension counter
\dimen0
contains the height of the column.
All the \...columns macros insert the value of the glue parameter
\abovecolumnskip
before the multicolumn text, and the value of the glue parameter
\belowcolumnskip
after it. The default value for both of these parameters is
\bigskipamount, i.e., one linespace in plain TeX.
The macros take into account only the insertion classes
defined by plain TeX; namely, footnotes and \topinserts. If
you have additional insertion classes, you will need to change
the implementation.
Also, Eplain makes insertions the full page width. There is no provision for column-width insertions.
The most common reference mark for footnotes is a raised number,
incremented on each footnote. The \numberedfootnote
macro provides this. It takes one argument, the footnote text.
If your document uses only numbered footnotes, you could make typing
\numberedfootnote more convenient with a command such as:
\let\footnote = \numberedfootnote
After doing this, you can type your footnotes as
\footnote{footnote text}, instead of as
\numberedfootnote{footnote text}.
Eplain keeps the current footnote number in the count register
\footnotenumber. So, to reset the footnote number to zero,
as you might want to do at, for example, the beginning of a chapter, you
could say \footnotenumber=0.
Plain TeX separates the footnote marker from the footnote text by
an en space (it uses the \textindent macro). In Eplain, you can
change this space by setting the dimension register
\footnotemarkseparation.
The default is still an en.
You can produce a space between footenotes by setting the glue
register \interfootnoteskip.
The default is zero.
\parskip is also set to zero by default before the beginning of
each footnote (but not for the text of the footnote).
You can also control footnote formatting in a more general way:
Eplain expands the token register \everyfootnote
before a footnote is typeset, but after the default values for all the
parameters have been established. For example, if you want your
footnotes to be printed in seven-point type, indented by one inch, you
could say:
\everyfootnote = {\sevenrm \leftskip = 1in}
By default, an \hrule is typeset above each group of footnotes
on a page. You can control the dimensions of this rule by setting
the dimension registers \footnoterulewidth
and \footnoteruleheight.
The space between the rule and the first footnote on the page is
determined by the dimension register \belowfootnoterulespace.
If you don't want any rule at all, set \footenoteruleheight=0pt,
and, most likely, \belowfootnoterulespace=0pt. The defaults for
these parameters typeset the rule in the same way as plain TeX: the
rule is 0.4 points high, 2 true inches wide, with 2.6 points below it.
The space above the rule and below the text on the page is controlled
by the glue register \skip\footins. The default is a plain TeX
\bigskip.
Exercise 11.6 of The TeXbook describes a macro \frac
for setting fractions, but \frac never made it into plain TeX.
So Eplain includes it.
\frac typesets the numerator and denominator in
\scriptfont0, slightly raised and lowered. The numerator and
denominator are separated by a slash. The denominator must be enclosed
in braces if it's more than one token long, but the numerator need not
be. (This is a consequence of \frac taking delimited arguments;
see page 203 of The TeXbook for an explanation of
delimited macro arguments.)
For example, \frac 23/{64} turns `23/64' into
.
When you typeset long pathnames, electronic mail addresses, or other
such “computer” names, you would like TeX to break lines at
punctuation characters within the name, rather than trying to find
hyphenation points within the words. For example, it would be better to
break the email address letters@alpha.gnu.ai.mit.edu at the
@ or a ., rather than at the hyphenation points in
letters and alpha.
If you use the \path macro to typeset the names, TeX will find
these good breakpoints. The argument to \path is delimited by
any character other other than \ which does not appear in the
name itself.
| is often a good choice, as in:
\path|letters@alpha.gnu.ai.mit.edu|
You can control the exact set of characters at which breakpoints will be
allowed by calling \discretionaries. This takes the same sort of
delimited argument; any character in the argument will henceforth be a valid
breakpoint within \path. The default set is essentially all the
punctuation characters:
\discretionaries |~!@$%^&*()_+`-=#{}[]:";'<>,.?\/|
If for some reason you absolutely must use \ as the delimiter
character for \path, you can set
\specialpathdelimiterstrue. (Other delimiter characters can
still be used.) TeX then processes the \path argument
about four times more slowly.
Eplain redefines the \TeX
macro of plain TeX to end with \null, so that the proper
spacing is produced when \TeX is used at the end of a sentence.
The other ...TeX macros listed here do this, also.
Eplain defines
\AMSTeX,
\BibTeX
\AMSLaTeX,
\LAMSTeX,
\LaTeX
\MF,
and \SLiTeX
to produce their respective logos. (Sorry, the logos are not shown
here.) Some spelling variants of these are also supported.
The solid rectangle that Eplain uses as a marker in unordered lists
(see Lists) is available by itself: just say \blackbox.
You can create black boxes of arbitrary size with \hrule or
\vrule.
You can also get unfilled rectangles with \makeblankbox.
This takes two explicit arguments: the height and depth of the rules that
define the top and bottom of the rectangle. (The two arguments are
added to get the width of the left and right borders, so that the
thickness of the border is the same on all four sides.) It also uses,
as implicit arguments, the dimensions of \box0 to define the
dimensions of the rectangle it produces. (The contents of \box0
are ignored.)
Here is an example. This small raised open box is suitable for putting next to numbers in, e.g., a table of contents.
\def\openbox{%
\ht0 = 1.75pt \dp0 = 1.75pt \wd0 = 3.5pt
\raise 2.75pt \makeblankbox{.2pt}{.2pt}
}
Finally, you can put a box around arbitrary text with \boxit.
This takes one argument, which must itself be a (TeX) box, and puts a
printed box around it, separated by \boxitspace
white space (3 points by default) on all four sides. For example:
\boxit{\hbox{This text is boxed.}}
The reason that the argument must be a box is that when the text is
more than one line long, TeX cannot figure out the line length for
itself. Eplain does set \parindent to zero inside \boxit,
since it is very unlikely you would want indentation there. (If you do,
you can always reset it yourself.)
\boxit uses \ehrule and \evrule so that you can
easily adjust the thicknesses of the box rules. See Rules.
This chapter describes definitions for producing commutative diagrams.
Steven Smith wrote this documentation (and the macros).
The macros \drawline
and \drawvector
provide the capability found in LaTeX's
picture mode to draw slanted lines and vectors of certain directions.
Both of these macros take three arguments: two integer arguments to
specify the direction of the line or vector, and one argument to specify
its length. For example, \drawvector(-4,1){60pt} produces the
vector
which lies in the 2d quadrant, has a slope of minus 1/4, and a width of
60 pt.
Note that if an \hbox is placed around \drawline or
\drawvector, then the width of the \hbox will be the
positive dimension specified in the third argument, except when a
vertical line or vector is specified, e.g.,
\drawline(0,1){1in}, which has zero width. If the specified
direction lies in the 1st or 2d quadrant (e.g., (1,1) or
(-2,3)), then the \hbox will have positive height and zero
depth. Conversely, if the specified direction lies in the 3d or 4th
quadrant (e.g., (-1,-1) or (2,-3)), then the \hbox
will have positive depth and zero height.
There are a finite number of directions that can be specified. For
\drawline, the absolute value of each integer defining the
direction must be less than or equal to six, i.e., (7,-1) is
incorrect, but (6,-1) is acceptable. For \drawvector, the
absolute value of each integer must be less than or equal to four.
Furthermore, the two integers cannot have common divisors; therefore, if
a line with slope 2 is desired, say (2,1) instead of
(4,2). Also, specify (1,0) instead of, say, (3,0)
for horizontal lines and likewise for vertical lines.
Finally, these macros depend upon the LaTeX font line10. If
your site doesn't have this font, ask your system administrator to get
it. Future enhancements will include macros to draw dotted lines and
dotted vectors of various directions.
The primitive commands \drawline and \drawvector can be
used to typeset arrow theoretic diagrams. This section describes (1)
macros to facilitate typesetting arrows and morphisms, and (2) macros to
facilitate the construction of commutative diagrams. All macros
described in this section must be used in math mode.
The macros \mapright and \mapleft produce right and left
pointing arrows, respectively. Use superscript (^) to place a
morphism above the arrow, e.g., \mapright^\alpha; use subscript
(_) to place a morphism below the arrow, e.g.,
\mapright_{\tilde l}. Superscripts and subscripts may be used
simulataneously, e.g., \mapright^\pi_{\rm epimor.}.
Similarly, the macros \mapup and \mapdown produce up and
down pointing arrows, respectively. Use \rt
to place a morphism to the right of the arrow, e.g., \mapup\rt{\rm
id}; use \lft
to place a morphism to the left of the arrow, e.g., \mapup\lft\omega.
\lft and \rt may be used simultaneously, e.g.,
\mapdown\lft\pi\rt{\rm monomor.}.
Slanted arrows are produced by the macro \arrow, which takes
a direction argument (e.g., \arrow(3,-4)). Use \rt and
\lft to place morphisms to the right and left, respectively, of
the arrow. A slanted line (no arrowhead) is produced with the macro
\sline,
whose syntax is identical to that of \arrow.
The length of these macros is predefined by the default TeX
dimensions \harrowlength,
for horizontal arrows (or lines),
\varrowlength,
for vertical arrows (or lines), and
\sarrowlength,
for slanted arrows (or lines). To change any of these dimensions, say,
e.g., \harrowlength=40pt. As with all other TeX dimensions,
the change may be as global or as local as you like. Furthermore, the
placement of morphisms on the arrows is controlled by the dimensions
\hmorphposn,
\vmorphposn,
and \morphdist.
The first two dimensions control the horizontal and vertical position of
the morphism from its default position; the latter dimension controls
the distance of the morphism from the arrow. If you have more than one
morphism per arrow (i.e., a ^/_ or \lft/\rt
construction), use the parameters
\hmorphposnup,
\hmorphposndn,
\vmorphposnup,
\vmorphposndn,
\hmorphposnrt,
\hmorphposnlft,
\vmorphposnrt,
and \vmorphposnlft.
The default values of all these dimensions are provided in the section
on parameters that follows below.
There is a family of macros to produce horizontal lines, arrows, and
adjoint arrows. The following macros produce horizontal maps and have
the same syntax as \mapright:
\mapright$X\mapright Y$
\mapleft$X\mapleft Y$
\hline$X\hline Y$
\bimapright$X\bimapright Y$
\bimapleft$X\bimapleft Y$
\adjmapright$X\adjmapright Y$
\adjmapleft$X\adjmapleft Y$
\bihline$X\bihline Y$
There is also a family of macros to produce vertical lines, arrows, and
adjoint arrows. The following macros produce vertical maps and have
the same syntax as \mapdown:
\mapdown\mapup\vline\bimapdown\bimapup\adjmapdown\adjmapup\bivlineFinally, there is a family of macros to produce slanted lines, arrows,
and adjoint arrows. The following macros produce slanted maps and have
the same syntax as \arrow:
\arrow\sline\biarrow\adjarrow\bislineThe width between double arrows is controlled by the parameter
\channelwidth.
The parameters \hchannel and \vchannel, if nonzero,
override \channelwidth by controlling the horizontal and vertical
shifting from the first arrow to the second.
There are no adornments on these arrows to distinguish inclusions from
epimorphisms from monomorphisms. Many texts, such as Lang's book
Algebra, use as a tasteful alternative the symbol `inc' (in roman) next
to an arrow to denote inclusion.
Future enhancements will include a mechanism to draw curved arrows
found in, e.g., the Snake Lemma, by employing a version of the
\path macros of Appendix D of The TeXbook.
There are two approaches to the construction of commutative diagrams
described here. The first approach, and the simplest, treats
commutative diagrams like fancy matrices, as Knuth does in Exercise
18.46 of The TeXbook. This case is covered by the macro
\commdiag,
which is an altered version of the Plain TeX macro \matrix.
An example suffices to demonstrate this macro. The following
commutative diagram (illustrating the covering homotopy property; Bott
and Tu, Differential Forms in Algebraic Topology)
is produced with the code
$$\commdiag{Y&\mapright^f&E\cr \mapdown&\arrow(3,2)\lft{f_t}&\mapdown\cr
Y\times I&\mapright^{\bar f_t}&X}$$
Of course, the parameters may be changed to produce a different effect. The following commutative diagram (illustrating the universal mapping property; Warner, Foundations of Differentiable Manifolds and Lie Groups) is produced with the code
$$\varrowlength=20pt
\commdiag{V\otimes W\cr \mapup\lft\phi&\arrow(3,-1)\rt{\tilde l}\cr
V\times W&\mapright^l&U\cr}$$
A diagram containing isosceles triangles is achieved by placing the apex of the triangle in the center column, as shown in the example (illustrating all constant minimal realizations of a linear system; Brockett, Finite Dimensional Linear Systems) which is produced with the code
$$\sarrowlength=.42\harrowlength
\commdiag{&R^m\cr &\arrow(-1,-1)\lft{\bf B}\quad \arrow(1,-1)\rt{\bf G}\cr
R^n&\mapright^{\bf P}&R^n\cr
\mapdown\lft{e^{{\bf A}t}}&&\mapdown\rt{e^{{\bf F}t}}\cr
R^n&\mapright^{\bf P}&R^n\cr
&\arrow(1,-1)\lft{\bf C}\quad \arrow(-1,-1)\rt{\bf H}\cr
&R^q\cr}$$
Other commutative diagram examples appear in the file
commdiags.tex, which is distributed with this package.
In these examples the arrow lengths and line slopes were carefully
chosen to blend with each other. In the first example, the default
settings for the arrow lengths are used, but a direction for the arrow
must be chosen. The ratio of the default horizontal and vertical arrow
lengths is approximately the golden mean
the arrow direction closest to this mean is (3,2). In the second
example, a slope of
is desired and the default horizontal arrow length is 60 pt; therefore,
choose a vertical arrow length of 20 pt. You may affect the interline
glue settings of \commdiag by redefining the macro
\commdiagbaselines.
(cf. Exercise 18.46 of The TeXbook and the section on
parameters below.)
The width, height, and depth of all morphisms are hidden so that the
morphisms' size do not affect arrow positions. This can cause a large
morphism at the top or bottom of a diagram to impinge upon the text
surrounding the diagram. To overcome this problem, use TeX's
\noalign primitive to insert a \vskip immediately above or
below the offending line, e.g.,
$$\commdiag{\noalign{\vskip6pt}X&\mapright^\int&Y\cr ...}.
The macro \commdiag is too simple to be used for more complicated
diagrams, which may have intersecting or overlapping arrows. A second
approach, borrowed from Francis Borceux's Diagram macros for
LaTeX, treats the commutative diagram like a grid of identically
shaped boxes. To compose the commutative diagram, first draw an equally
spaced grid, e.g.,
on a piece of scratch paper. Then draw each element (vertices and
arrows) of the commutative diagram on this grid, centered at each
grid point. Finally, use the macro \gridcommdiag
to implement your design as a TeX alignment. For example, the cubic
diagram
that appears in Francis Borceux's documentation can be implemented on
a 7 by 7 grid, and is achieved with the code
$$\harrowlength=48pt \varrowlength=48pt \sarrowlength=20pt
\def\cross#1#2{\setbox0=\hbox{$#1$}%
\hbox to\wd0{\hss\hbox{$#2$}\hss}\llap{\unhbox0}}
\gridcommdiag{&&B&&\mapright^b&&D\cr
&\arrow(1,1)\lft a&&&&\arrow(1,1)\lft d\cr
A&&\cross{\hmorphposn=12pt\mapright^c}{\vmorphposn=-12pt\mapdown\lft f}
&&C&&\mapdown\rt h\cr\cr
\mapdown\lft e&&F&&\cross{\hmorphposn=-12pt\mapright_j}
{\vmorphposn=12pt\mapdown\rt g}&&H\cr
&\arrow(1,1)\lft i&&&&\arrow(1,1)\rt l\cr
E&&\mapright_k&&G\cr}$$
The dimensions \hgrid and \vgrid
control the horizontal and vertical spacing of the grid used by
\gridcommdiag. The default setting for both of these dimensions
is 15 pt. Note that in the example of the cube the arrow lengths must
be adjusted so that the arrows overlap into neighboring boxes by the
desired amount. Hence, the \gridcommdiag method, albeit more
powerful, is less automatic than the simpler \commdiag method.
Furthermore, the ad hoc macro \cross is introduced to allow the
effect of overlapping arrows. Finally, note that the positions of four
of the morphisms are adjusted by setting \hmorphposn and
\vmorphposn.
One is not restricted to a square grid. For example, the proof of Zassenhaus's Butterfly Lemma can be illustrated by the diagram (appearing in Lang's book Algebra) This diagram may be implemented on a 9 by 12 grid with an aspect ratio of 1/2, and is set with the code
$$\hgrid=16pt \vgrid=8pt \sarrowlength=32pt
\def\cross#1#2{\setbox0=\hbox{$#1$}%
\hbox to\wd0{\hss\hbox{$#2$}\hss}\llap{\unhbox0}}
\def\l#1{\llap{$#1$\hskip.5em}}
\def\r#1{\rlap{\hskip.5em$#1$}}
\gridcommdiag{&&U&&&&V\cr &&\bullet&&&&\bullet\cr
&&\sarrowlength=16pt\sline(0,1)&&&&\sarrowlength=16pt\sline(0,1)\cr
&&\l{u(U\cap V)}\bullet&&&&\bullet\r{(U\cap V)v}\cr
&&&\sline(2,-1)&&\sline(2,1)\cr
&&\cross{=}{\sline(0,1)}&&\bullet&&\cross{=}{\sline(0,1)}\cr\cr
&&\l{^{\textstyle u(U\cap v)}}\bullet&&\cross{=}{\sline(0,1)}&&
\bullet\r{^{\textstyle(u\cap V)v}}\cr
&\sline(2,1)&&\sline(2,-1)&&\sline(2,1)&&\sline(2,-1)\cr
\l{u}\bullet&&&&\bullet&&&&\bullet\r{v}\cr
&\sline(2,-1)&&\sline(2,1)&&\sline(2,-1)&&\sline(2,1)\cr
&&\bullet&&&&\bullet\cr &&u\cap V&&&&U\cap v\cr}$$
Again, the construction of this diagram requires careful choices for the
arrow lengths and is facilitated by the introduction of the ad hoc
macros \cross, \r, and \l. Note also that
superscripts were used to adjust the position of the vertices
Many diagrams may be typeset with the predefined macros that appear
here; however, ingenuity is often required to handle special cases.
The following is a list describing the parameters used in the commutative diagram macros. These dimensions may be changed globally or locally.
\harrowlength\varrowlength\harrowlength) The length of up or down
arrows.
\sarrowlength\hmorphposn\hmorphposnup,
\hmorphposndn,
\hmorphposnrt,
and \hmorphposnlft
for ^/_ or \lft/\rt constructions.
\vmorphposn\vmorphposnup,
\vmorphposndn,
\vmorphposnrt,
and \vmorphposnlft
for ^/_ or \lft/\rt constructions.
\morphdist\channelwidth\hchannel, \vchannel\channelwidth. The
horizontal and vertical shifts between double lines or arrows.
\commdiagbaselines\baselineskip=15pt
\lineskip=3pt
\lineskiplimit=3pt )
The parameters used by \commdiag for setting interline glue.
\hgrid\gridcommdiag.
\vgrid\gridcommdiag.
The definitions in this section are only likely to be useful when you are writing nontrivial macros, not when writing a document.
Plain TeX defines \active (as the number 13) for use in
changing category codes. Although the author of The TeXbook
has “intentionally kept the category codes numeric”, two other
categories are commonly used: letters (category code 11) and others
(12). Therefore, Eplain defines \letter and
\other.
Sometimes it is cleaner to make a character active without actually
writing a \catcode command. The \makeactive command takes
a character as an argument to make active (and ignores following
spaces). For example, here are two commands which both make \
active:
\makeactive`\\ \makeactive92
Usually, when you give a definition to an active character, you have
to do so inside a group where you temporarily make the character active,
and then give it a global definition (cf. the definition of
\obeyspaces in The TeXbook).
This is inconvenient if you are writing a long macro, or if the
character already has a global definition you do not wish to transcend.
Eplain provides \letreturn, which defines the usual end-of-line
character to be the argument. For example:
\def\mymacro{... \letreturn\myreturn ... }
\mymacro hello
there
The end-of-line between hello and there causes
\myreturn to be expanded.
The TeXbook describes \uncatcodespecials,
which makes all characters which are normally “special” into “other”
characters, but the definition never made it into plain TeX.
Eplain therefore defines it.
Finally, \percentchar
expands into a literal `%' character. This is useful when you
\write TeX output to a file, and want to avoid spurious
spaces. For example, Eplain writes a \percentchar after the
definition of cross-references. The macros \lbracechar
and \rbracechar
expand similarly.
Plain TeX provides macros that allocate registers of each primitive
type in TeX, to prevent different sets of macros from using the same
register for two different things. The macros are all named starting
with new,
e.g., \newcount allocates a new “count”
(integer) register. Such allocations are usually needed only at the top
level of some macro definition file; therefore, plain TeX makes the
allocation registers \outer,
to help find errors. (The error this helps to find is a missing right
brace in some macro definition.)
Sometimes, however, it is useful to allocate a register as part of
some macro. An outer control sequence cannot be used as part of a macro
definition (or in a few other contexts: the parameter text of a
definition, an argument to a definition, the preamble of an alignment,
or in conditional text that is being skipped). Therefore, Eplain
defines “inner” versions of all the allocation macros, named with the
prefix inner:
\innernewbox,
\innernewcount,
\innernewdimen,
\innernewfam,
\innernewhelp,
\innernewif,
\innernewinsert,
\innernewlanguage,
\innernewread,
\innernewskip,
\innernewtoks,
\innernewwrite.
You can also define non-outer versions of other macros in the same way
that Eplain defines the above. The basic macro is called
\innerdef:
\innerdef \innername {outername}
The first argument (\innername) to \innerdef is the
control sequence that you want to define. Any previous definition of
\innername is replaced. The second argument
(outername) is the characters in the name of the outer
control sequence. (You can't use the actual control sequence name,
since it's outer!)
If the outer control sequence is named \cs, and you want to
define innercs as the inner one, you can use
\innerinnerdef,
which is just an abbreviation for a call to \innerdef. For
example, these two calls are equivalent:
\innerdef\innerproclaim{proclaim}
\innerinnerdef{proclaim}
You can iterate through a comma-separated list of items with
\for.
Here is an example:
\for\name:=karl,kathy\do{%
\message{\name}%
}%
This writes karl and kathy to the terminal. Spaces
before or after the commas in the list, or after the :=, are
not ignored.
\for expands the iterated values fully (with \edef), so
this is equivalent to the above:
\def\namelist{karl,kathy}%
\for\name:=\namelist\do ...
It is occasionally useful to redefine a macro that takes arguments to
do nothing. Eplain defines \gobble,
\gobbletwo,
and \gobblethree to swallow one, two, and three arguments,
respectively.
For example, if you want to produce a “short” table of
contents—one that includes only chapters, say—the easiest thing to
do is read the entire .toc file (see Contents), and just
ignore the commands that produce section or subsection entries. To be
specific:
\let\tocchapterentry = \shorttocchapter
\let\tocsectionentry = \gobbletwo
\let\tocsubsectionentry = \gobbletwo
\readtocfile
(Of course, this assumes you only have chapters, sections, and subsections in your document.)
In addition, Eplain defines \eattoken
to swallow the single following token, using \let. Thus,
\gobble followed by {...} ignores the entire
brace-enclosed text. \eattoken followed by the same ignores only
the opening left brace.
Eplain defines a macro \identity
which takes one argument and expands to that argument. This may be
useful if you want to provide a function for the user to redefine, but
don't need to do anything by default. (For example, the default
definition of \eqconstruct (see Formatting equation references) is \identity.)
You may also want to read an optional argument. The established
convention is that optional arguments are put in square brackets, so
that is the syntax Eplain recognizes. Eplain ignores space tokens
before an optional argument, via \futurenonspacelet.
You test for an optional argument by using \@getoptionalarg.
It takes one argument, a control sequence to expand after reading the
argument, if present. If an optional argument is present, the control
sequence \@optionalarg expands to it; otherwise,
\@optionalarg is \empty. You must therefore have the
category code of @ set to 11 (letter). Here is an example:
\catcode`@=\letter
\def\cmd{\@getoptionalarg\finishcmd}
\def\finishcmd{%
\ifx\@optionalarg\empty
% No optional argument present.
\else
% One was present.
\fi
}
If an optional argument contains another optional argument, the inner one will need to be enclosed in braces, so TeX does not mistake the end of the first for the end of the second.
Eplain defines \xrlabel
to produce control sequence names for cross-reference labels, et al.
This macro expands to its argument with an _ appended. (It does
this because the usual use of \xrlabel is to generate a control
sequence name, and we naturally want to avoid conflicts between control
sequence names.)
Because \xrlabel is fully expandable, to make a control
sequence name out of the result you need only do
\csname \xrlabel{label}\endcsname
The \csname primitive makes a control sequence name out
of any sequence of character tokens, regardless of category code.
Labels can therefore include any characters except for \,
{, }, and #, all of which are used in macro
definitions themselves.
\sanitize takes a control sequence as an argument and converts
the expansion of the control sequence into a list of character tokens.
This is the behavior you want when writing information like chapter
titles to an output file. For example, here is part of the definition
of \writenumberedtocentry; #2 is the title that the user
has given.
...
\def\temp{#2}%
...
\write\tocfile{%
...
\sanitize\temp
...
}%
This section describes some miscellanous macros for expansion, etc.
\csn and \ece\csn{name} simply abbreviates \csname name
\encsname, thus saving some typing. The extra level of expansion
does take some time, though, so I don't recommend it for an inner loop.
\expandafter token \csname name \endcsname
For example,
\def\fontabbrevdef#1#2{\ece\def{@#1font}{#2}}
\fontabbrevdef{normal}{ptmr}
defines a control sequence \@normalfont to expand to
ptmr.
\edefappend\edefappend is a way of adding on to an existing definition. It
takes two arguments: the first is the control sequence name, the second
the new tokens to append to the definition. The second argument is
fully expanded (in the \edef that redefines the control sequence).
For example:
\def\foo{abc}
\def\bar{xyz}
\edefappend\foo{\bar karl}
results in \foo being defined as abcxyzkarl.
A hook is simply a name for a group of actions which is executed
in certain places—presumably when it is most useful to allow
customization or modification. TeX already provides many builtin
hooks; for example, the \every ... token lists are all
examples of hooks.
Eplain provides several macros for adding actions to hooks. They all take two arguments: the name of the hook and the new actions.
hookaction name actionshookappend name actionshookprepend name actionshookactiononce name \cs\hookactiononce adds cs to name, like the macros
above, but first it adds
\global\let \cs \relax
to the definition of \cs. (This implies \cs must
be a true expandable macro, not a control sequence \let to a
primitive or some other such thing.) Thus, \cs is expanded the
next time the hook name is run, but it will disappear after that.
The \global is useful because \hookactiononce is most
useful when the grouping structure of the TeX code could be anything.
Neither this nor the other hook macros do global assignments to the hook
variable itself, so TeX's usual grouping rules apply.
The companion macro to defining hook actions is \hookrun, for
running them. This takes a single argument, the name of the hook. If
no actions for the hook are defined, no error ensues.
Here is a skeleton of general \begin and \end macros that
run hooks, and a couple of calls to define actions. The use of
\hookprepend for the begin action and \hookappend for the
end action ensures that the actions are executed in proper sequence with
other actions (as long as the other actions use \hookprepend and
\hookappend also).
\def\begin#1{ ... \hookrun{begin} ... }
\def\end#1{ ... \hookrun{end} ... }
\hookprepend{begin}\start_underline
\hookappend{end}\finish_underline
A property is a name/value pair associated with another symbol, traditionally called an atom. Both atom and property names are control sequence names.
Eplain provides two macros for dealing with property lists:
\setproperty and \getproperty.
\setproperty atom propname value\setproperty defines the property property on the atom
atom to be value. atom and propname can be
anything acceptable to \csname. value can be anything.
\getproperty atom propname\getproperty expands to the value stored for propname on
atom. If propname is undefined, it expands to nothing
(i.e., \empty).
The idea of properties originated in Lisp (I believe). There, the implementation truly does associate properties with atoms. In TeX, where we have no builtin support for properties, the association is only conceptual.
The following example typesets xyz.
\setproperty{a}{pr}{xyz}
\getproperty{a}{pr}
\expandonce\expandonce is defined as \expandafter\noexpand. Thus,
\expandonce token expands token once, instead of to
TeX primitives. This is most useful in an \edef.
For example, the following defines \temp to be \foo, not
abc.
\def\foo{abc}
\def\bar{\foo}
\edef\temp{\expandonce\bar}
\ifundefined\ifundefined{cs} t \else f \fi expands the
t text if the control sequence \cs is undefined or
has been \let to \relax, and the f text otherwise.
Since \ifundefined is not a primitive conditional, it cannot be
used in places where TeX might skip tokens “at high speed”, e.g.,
within another conditional—TeX can't match up the \if's and
\fi's.
This macro was taken directly from The TeXbook, page 308.
\futurenonspaceletThe \futurelet primitive allows you to look at the next token
from the input. Sometimes, though, you want to look ahead ignoring any
spaces. This is what \futurenonspacelet does. It is otherwise
the same as \futurelet: you give it two control sequences as
arguments, and it assigns the next nonspace token to the first, and then
expands the second. For example:
\futurenonspacelet\temp\finishup
\def\finishup{\ifx\temp ...}
\obeywhitespace makes both end-of-lines and space characters in
the input be respected in the output. Unlike plain TeX's
\obeyspaces, even spaces at the beginnings of lines turn into
blank space.
By default, the size of the space that is produced by a space
character is the natural space of the current font, i.e.,
what \ produces.
Ordinarily, a blank line in the input produces as much blank vertical
space as a line of text would occupy. You can adjust this by assigning
to the parameter \blanklineskipamount:
if you set this negative, the space produced by a blank line will be
smaller; if positive, larger.
Tabs are not affected by this routine. In particular, if tabs occur at the beginning of a line, they will disappear. (If you are trying to make TeX do the “right thing” with tabs, don't. Use a utility program like expand instead.)
\numbername
produces the written-out form of its argument, i.e., `zero' through
`ten' for the numbers 0–10, and numerals for all others.
TeX's built-in \penalty command simply appends to the
current list, no matter what kind of list it is. You might intend a
particular penalty to always be a “vertical” penalty, however, i.e.,
appended to a vertical list. Therefore, Eplain provides
\vpenalty
and \hpenalty
which first leave the other mode and then do \penalty.
More precisely, \vpenalty inserts \par if the current
mode is horizontal, and \hpenalty inserts \leavevmode if
the current mode is vertical. (Thus, \vpenalty cannot be used in
math mode.)
It is common to write some information out to a file to be used on a
subsequent run. But when it is time to read the file again, you only
want to do so if the file actually exists. \testfileexistence
is given an argument which is appended to \jobname,
and sets the conditional \iffileexists
appropriately.
For example:
\testfileexistence{toc}%
\iffileexists
\input \jobname.toc
\fi
Plain TeX does not provide “named” block structures, only the anonymous
\begingroup and \endgroup pair. The disadvantage of this
is that when there are several such groups and one is mismatched, it can
be difficult to find the error. Eplain provides a named block structure
so that if you forget an \environment or an
\endenvironment, you will (probably) get an error message about
it.
For example:
\def\itpar{
\environment{@italicpar}
\it\par
}
\def\enditpar{
\par
\endenvironment{@italicpar}%
}
which could then be used to set italicized paragraphs:
\itpar
If I reprehend anything in this world, it is the use of my oracular
tongue, and a nice derangement of epitaphs!
\enditpar
The above sort of environment allows nesting. But environments
shouldn't always be allowed to nest. Put the control sequence
\checkenv at the beginning of a macro that is going to define an
environment that should not be nested.
Copyright © 1989, 1991 Free Software Foundation, Inc.
59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
Everyone is permitted to copy and distribute verbatim copies
of this license document, but changing it is not allowed.
The licenses for most software are designed to take away your freedom to share and change it. By contrast, the GNU General Public License is intended to guarantee your freedom to share and change free software—to make sure the software is free for all its users. This General Public License applies to most of the Free Software Foundation's software and to any other program whose authors commit to using it. (Some other Free Software Foundation software is covered by the GNU Library General Public License instead.) You can apply it to your programs, too. When we speak of free software, we are referring to freedom, not price. Our General Public Licenses are designed to make sure that you have the freedom to distribute copies of free software (and charge for this service if you wish), that you receive source code or can get it if you want it, that you can change the software or use pieces of it in new free programs; and that you know you can do these things. To protect your rights, we need to make restrictions that forbid anyone to deny you these rights or to ask you to surrender the rights. These restrictions translate to certain responsibilities for you if you distribute copies of the software, or if you modify it. For example, if you distribute copies of such a program, whether gratis or for a fee, you must give the recipients all the rights that you have. You must make sure that they, too, receive or can get the source code. And you must show them these terms so they know their rights. We protect your rights with two steps: (1) copyright the software, and (2) offer you this license which gives you legal permission to copy, distribute and/or modify the software. Also, for each author's protection and ours, we want to make certain that everyone understands that there is no warranty for this free software. If the software is modified by someone else and passed on, we want its recipients to know that what they have is not the original, so that any problems introduced by others will not reflect on the original authors' reputations. Finally, any free program is threatened constantly by software patents. We wish to avoid the danger that redistributors of a free program will individually obtain patent licenses, in effect making the program proprietary. To prevent this, we have made it clear that any patent must be licensed for everyone's free use or not licensed at all. The precise terms and conditions for copying, distribution and modification follow.
If you develop a new program, and you want it to be of the greatest possible use to the public, the best way to achieve this is to make it free software which everyone can redistribute and change under these terms. To do so, attach the following notices to the program. It is safest to attach them to the start of each source file to most effectively convey the exclusion of warranty; and each file should have at least the “copyright” line and a pointer to where the full notice is found.
one line to give the program's name and a brief idea of what it does.
Copyright (C) yyyy name of author
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
Also add information on how to contact you by electronic and paper mail. If the program is interactive, make it output a short notice like this when it starts in an interactive mode:
Gnomovision version 69, Copyright (C) 19yy name of author
Gnomovision comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
This is free software, and you are welcome to redistribute it
under certain conditions; type `show c' for details.
The hypothetical commands show w and show c should show the appropriate parts of the General Public License. Of course, the commands you use may be called something other than show w and show c; they could even be mouse-clicks or menu items—whatever suits your program. You should also get your employer (if you work as a programmer) or your school, if any, to sign a “copyright disclaimer” for the program, if necessary. Here is a sample; alter the names:
Yoyodyne, Inc., hereby disclaims all copyright interest in the program
`Gnomovision' (which makes passes at compilers) written by James Hacker.
signature of Ty Coon, 1 April 1989
Ty Coon, President of Vice
This General Public License does not permit incorporating your program into proprietary programs. If your program is a subroutine library, you may consider it more useful to permit linking proprietary applications with the library. If this is what you want to do, use the GNU Library General Public License instead of this License.
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