Texinfo provides several commands for inserting characters that have special meaning in Texinfo, such as braces, and for other graphic elements that do not correspond to simple characters you can type.
`@' and curly braces are special characters in Texinfo. To insert these characters so they appear in text, you must put an `@' in front of these characters to prevent Texinfo from misinterpreting them.
Do not put braces after any of these commands; they are not necessary.
@@ stands for a single `@' in either printed or Info
output.
Do not put braces after an @@ command.
@{ stands for a single `{' in either printed or Info
output.
@} stands for a single `}' in either printed or Info
output.
Do not put braces after either an @{ or an @}
command.
The following sections describe commands that control spacing of various kinds within and after sentences.
Depending on whether a period or exclamation point or question mark is inside or at the end of a sentence, less or more space is inserted after a period in a typeset manual. Since it is not always possible to determine when a period ends a sentence and when it is used in an abbreviation, special commands are needed in some circumstances. Usually, Texinfo can guess how to handle periods, so you do not need to use the special commands; you just enter a period as you would if you were using a typewriter, which means you put two spaces after the period, question mark, or exclamation mark that ends a sentence.
Use the @: command after a period, question mark,
exclamation mark, or colon that should not be followed by extra space.
For example, use @: after periods that end abbreviations
which are not at the ends of sentences.
For example,
The s.o.p.@: has three parts ... The s.o.p. has three parts ...
produces
The s.o.p. has three parts ...
The s.o.p. has three parts ...
(Incidentally, `s.o.p.' is an abbreviation for "Standard Operating Procedure".)
@: has no effect on the Info output. Do not put braces after
@:.
Use @. instead of a period, @! instead of an
exclamation point, and @? instead of a question mark at the end
of a sentence that ends with a single capital letter. Otherwise, TeX
will think the letter is an abbreviation and will not insert the correct
end-of-sentence spacing. Here is an example:
Give it to M.I.B. and to M.E.W@. Also, give it to R.J.C@. Give it to M.I.B. and to M.E.W. Also, give it to R.J.C.
produces
Give it to M.I.B. and to M.E.W. Also, give it to R.J.C.
Give it to M.I.B. and to M.E.W. Also, give it to R.J.C.
In the Info file output, @. is equivalent to a simple
`.'; likewise for @! and @?.
The meanings of @: and @. in Texinfo are designed to
work well with the Emacs sentence motion commands (see section `Sentences' in The GNU Emacs Manual).
Do not put braces after any of these commands.
Ordinarily, TeX collapses multiple whitespace characters (space, tab, and newline) into a single space. Info output, on the other hand, preserves whitespace as you type it, except for changing a newline into a space; this is why it is important to put two spaces at the end of sentences in Texinfo documents.
Occasionally, you may want to actually insert several consecutive
spaces, either for purposes of example (what your program does with
multiple spaces as input), or merely for purposes of appearance in
headings or lists. Texinfo supports three commands:
@SPACE, @TAB, and @NL, all of
which insert a single space into the output. (Here,
@SPACE represents an `@' character followed by a
space, i.e., `@ ', and TAB and NL represent the tab
character and end-of-line, i.e., when `@' is the last character on
a line.)
For example,
Spacey@ @ @ @ example.
produces
Spacey example.
Other possible uses of @SPACE have been subsumed by
@multitable (see section 11.5 Multi-column Tables).
Do not follow any of these commands with braces.
@dmn{dimension}: Format a Dimension
At times, you may want to write `12pt' or
`8.5in' with little or no space between the number and the
abbreviation for the dimension. You can use the @dmn command
to do this. On seeing the command, TeX inserts just enough space
for proper typesetting; the Info formatting commands insert no space
at all, since the Info file does not require it.
To use the @dmn command, write the number and then follow it
immediately, with no intervening space, by @dmn, and then by
the dimension within braces. For example,
A4 paper is 8.27@dmn{in} wide.
produces
A4 paper is 8.27in wide.
Not everyone uses this style. Some people prefer `8.27 in.@:'
or `8.27 inches' to `8.27@dmn{in}' in the Texinfo file.
In these cases, however, the formatters may insert a line break between
the number and the dimension, so use @w (see section 14.4 @w{text}: Prevent Line Breaks). Also, if
you write a period after an abbreviation within a sentence, you should
write `@:' after the period to prevent TeX from inserting extra
whitespace, as shown here. See section 13.2.1 Not Ending a Sentence.
Here is a table with the commands Texinfo provides for inserting
floating accents. The commands with non-alphabetic names do not take
braces around their argument (which is taken to be the next character).
(Exception: @, does take braces around its argument.)
This is so as to make the source as convenient to type and read as
possible, since accented characters are very common in some languages.
An ellipsis (a line of dots) is not typeset as a string of
periods, so a special command is used for ellipsis in Texinfo. The
@bullet command is special, too. Each of these commands is
followed by a pair of braces, `{}', without any whitespace
between the name of the command and the braces. (You need to use braces
with these commands because you can use them next to other text; without
the braces, the formatters would be confused. See section I. @-Command Syntax, for further information.)
@dots{} (...) and @enddots{} (@enddots{})
Use the @dots{} command to generate an ellipsis, which is
three dots in a row, appropriately spaced, like this: `...'. Do
not simply write three periods in the input file; that would work for
the Info file output, but would produce the wrong amount of space
between the periods in the printed manual.
Similarly, the @enddots{} command generates an
end-of-sentence ellipsis (four dots) @enddots{}
@bullet{} (*)
Use the @bullet{} command to generate a large round dot, or
the closest possible thing to one. In Info, an asterisk is used.
Here is a bullet: *
When you use @bullet in @itemize, you do not need to
type the braces, because @itemize supplies them.
(See section 11.2 @itemize: Making an Itemized List.)
The logo `TeX' is typeset in a special fashion and it needs an @-command. The copyright symbol, `(C)', is also special. Each of these commands is followed by a pair of braces, `{}', without any whitespace between the name of the command and the braces.
@copyright{}.
@TeX{} (TeX)
Use the @TeX{} command to generate `TeX'. In a printed
manual, this is a special logo that is different from three ordinary
letters. In Info, it just looks like `TeX'. The
@TeX{} command is unique among Texinfo commands in that the
`T' and the `X' are in upper case.
@copyright{} ((C))
Use the @copyright{} command to generate `(C)'. In
a printed manual, this is a `c' inside a circle, and in Info,
this is `(C)'.
@pounds{} (@pounds{}): Pounds Sterling
Use the @pounds{} command to generate `@pounds{}'. In a
printed manual, this is the symbol for the currency pounds sterling.
In Info, it is a `#'. Other currency symbols are unfortunately not
available.
@minus{} (-): Inserting a Minus Sign
Use the @minus{} command to generate a minus sign. In a
fixed-width font, this is a single hyphen, but in a proportional font,
the symbol is the customary length for a minus sign--a little longer
than a hyphen, shorter than an em-dash:
`-' is a minus sign generated with `@minus{}',
`-' is a hyphen generated with the character `-',
`---' is an em-dash for text.
In the fixed-width font used by Info, @minus{} is the same
as a hyphen.
You should not use @minus{} inside @code or
@example because the width distinction is not made in the
fixed-width font they use.
When you use @minus to specify the mark beginning each entry in
an itemized list, you do not need to type the braces
(see section 11.2 @itemize: Making an Itemized List.)
@math: Inserting Mathematical Expressions
You can write a short mathematical expression with the @math
command. Write the mathematical expression between braces, like this:
@math{(a + b)(a + b) = a^2 + 2ab + b^2}
This produces the following in Info:
(a + b)(a + b) = a^2 + 2ab + b^2
Thus, the @math command has no effect on the Info output.
For complex mathematical expressions, you can also use TeX directly (see section 16.3 Raw Formatter Commands). When you use TeX directly, remember to write the mathematical expression between one or two `$' (dollar-signs) as appropriate.
In Texinfo, code is often illustrated in examples that are delimited
by @example and @end example, or by @lisp and
@end lisp. In such examples, you can indicate the results of
evaluation or an expansion using `=>' or
`==>'. Likewise, there are commands to insert glyphs
to indicate
printed output, error messages, equivalence of expressions, and the
location of point.
The glyph-insertion commands do not need to be used within an example, but most often they are. Every glyph-insertion command is followed by a pair of left- and right-hand braces.
Here are the different glyph commands:
@result{} points to the result of an expression.
@expansion{} shows the results of a macro expansion.
@print{} indicates printed output.
@error{} indicates that the following text is an error
message.
@equiv{} indicates the exact equivalence of two forms.
@point{} shows the location of point.@result{} (=>): Indicating Evaluation
Use the @result{} command to indicate the result of
evaluating an expression.
The @result{} command is displayed as `=>' in Info
and as a double stemmed arrow in the printed output.
Thus, the following,
(cdr '(1 2 3))
=> (2 3)
may be read as "(cdr '(1 2 3)) evaluates to (2 3)".
@expansion{} (==>): Indicating an Expansion
When an expression is a macro call, it expands into a new expression.
You can indicate the result of the expansion with the
@expansion{} command.
The @expansion{} command is displayed as `==>'
in Info and as a long arrow with a flat base in the printed output.
For example, the following
@lisp
(third '(a b c))
@expansion{} (car (cdr (cdr '(a b c))))
@result{} c
@end lisp
produces
(third '(a b c))
==> (car (cdr (cdr '(a b c))))
=> c
which may be read as:
(third '(a b c))expands to(car (cdr (cdr '(a b c)))); the result of evaluating the expression isc.
Often, as in this case, an example looks better if the
@expansion{} and @result{} commands are indented
five spaces.
@print{} (-|): Indicating Printed Output
Sometimes an expression will print output during its execution. You
can indicate the printed output with the @print{} command.
The @print{} command is displayed as `-|' in Info
and similarly, as a horizontal dash butting against a vertical bar, in
the printed output.
In the following example, the printed text is indicated with `-|', and the value of the expression follows on the last line.
(progn (print 'foo) (print 'bar))
-| foo
-| bar
=> bar
In a Texinfo source file, this example is written as follows:
@lisp
(progn (print 'foo) (print 'bar))
@print{} foo
@print{} bar
@result{} bar
@end lisp
@error{} (error-->): Indicating an Error Message
A piece of code may cause an error when you evaluate it. You can
designate the error message with the @error{} command.
The @error{} command is displayed as `error-->' in Info
and as the word `error' in a box in the printed output.
Thus,
@lisp
(+ 23 'x)
@error{} Wrong type argument: integer-or-marker-p, x
@end lisp
produces
(+ 23 'x) error--> Wrong type argument: integer-or-marker-p, x
This indicates that the following error message is printed when you evaluate the expression:
Wrong type argument: integer-or-marker-p, x
`error-->' itself is not part of the error message.
@equiv{} (==): Indicating Equivalence
Sometimes two expressions produce identical results. You can indicate the
exact equivalence of two forms with the @equiv{} command.
The @equiv{} command is displayed as `==' in Info
and as a three parallel horizontal lines in the printed output.
Thus,
@lisp
(make-sparse-keymap) @equiv{} (list 'keymap)
@end lisp
produces
(make-sparse-keymap) == (list 'keymap)
This indicates that evaluating (make-sparse-keymap) produces
identical results to evaluating (list 'keymap).
@point{} (-!-): Indicating Point in a BufferSometimes you need to show an example of text in an Emacs buffer. In such examples, the convention is to include the entire contents of the buffer in question between two lines of dashes containing the buffer name.
You can use the `@point{}' command to show the location of point in the text in the buffer. (The symbol for point, of course, is not part of the text in the buffer; it indicates the place between two characters where point is located.)
The @point{} command is displayed as `-!-' in Info
and as a small five pointed star in the printed output.
The following example shows the contents of buffer `foo' before
and after evaluating a Lisp command to insert the word changed.
---------- Buffer: foo ---------- This is the -!-contents of foo. ---------- Buffer: foo ----------
(insert "changed ")
=> nil
---------- Buffer: foo ----------
This is the changed -!-contents of foo.
---------- Buffer: foo ----------
In a Texinfo source file, the example is written like this:
@example
---------- Buffer: foo ----------
This is the @point{}contents of foo.
---------- Buffer: foo ----------
(insert "changed ")
@result{} nil
---------- Buffer: foo ----------
This is the changed @point{}contents of foo.
---------- Buffer: foo ----------
@end example
A footnote is for a reference that documents or elucidates the primary text.(8)
In Texinfo, footnotes are created with the @footnote command.
This command is followed immediately by a left brace, then by the text
of the footnote, and then by a terminating right brace. Footnotes may
be of any length (they will be broken across pages if necessary), but
are usually short. The template is:
ordinary text@footnote{text of footnote}
As shown here, the @footnote command should come right after the
text being footnoted, with no intervening space; otherwise, the footnote
marker might end up starting a line.
For example, this clause is followed by a sample footnote(9); in the Texinfo source, it looks like this:
...a sample footnote@footnote{Here is the sample
footnote.}; in the Texinfo source...
In a printed manual or book, the reference mark for a footnote is a small, superscripted number; the text of the footnote appears at the bottom of the page, below a horizontal line.
In Info, the reference mark for a footnote is a pair of parentheses with the footnote number between them, like this: `(1)'. The reference mark is followed by a cross-reference link to the footnote's text.
In the HTML output, footnote references are marked with a small, superscripted number which is rendered as a hypertext link to the footnote text.
By the way, footnotes in the argument of an @item command for a
@table must be on the same line as the @item
(as usual). See section 11.4 Making a Two-column Table.
Info has two footnote styles, which determine where the text of the footnote is located:
--------- Footnotes --------- (1) Here is a sample footnote.
File: texinfo.info Node: Overview-Footnotes, Up: Overview (1) The first syllable of "Texinfo" is pronounced like "speck", not "hex". ...
A Texinfo file may be formatted into an Info file with either footnote style.
Use the @footnotestyle command to specify an Info file's
footnote style. Write this command at the beginning of a line followed
by an argument, either `end' for the end node style or
`separate' for the separate node style.
For example,
@footnotestyle end
or
@footnotestyle separate
Write an @footnotestyle command before or shortly after the
end-of-header line at the beginning of a Texinfo file. (If you
include the @footnotestyle command between the start-of-header
and end-of-header lines, the region formatting commands will format
footnotes as specified.)
If you do not specify a footnote style, the formatting commands use
their default style. Currently, texinfo-format-buffer and
texinfo-format-region use the `separate' style and
makeinfo uses the `end' style.
This chapter contains two footnotes.
You can insert an image given in an external file with the
@image command:
@image{filename, [width], [height]}
The filename argument is mandatory, and must not have an extension, because the different processors support different formats:
makeinfo uses `filename.txt' verbatim for
Info output (more or less as if it was an @example).
makeinfo producing HTML output tries `filename.png';
if that does not exist, it tries `filename.jpg'. If that
does not exist either, it complains. (We cannot support GIF format due
to patents.)
The optional width and height arguments specify the size to scale the image to (they are ignored for Info output). If neither is specified, the image is presented in its natural size (given in the file); if only one is specified, the other is scaled proportionately; and if both are specified, both are respected, thus possibly distorting the original image by changing its aspect ratio.
The width and height may be specified using any valid TeX dimension, namely:
For example, the following will scale a file `ridt.eps' to one inch vertically, with the width scaled proportionately:
@image{ridt,,1in}
For @image to work with TeX, the file `epsf.tex' must be
installed somewhere that TeX can find it. (The standard location is
`texmf/tex/generic/dvips/epsf.tex', where texmf is a
root of your TeX directory tree.) This file is included in the
Texinfo distribution and is available from
ftp://tug.org/tex/epsf.tex.
@image can be used within a line as well as for displayed
figures. Therefore, if you intend it to be displayed, be sure to leave
a blank line before the command, or the output will run into the
preceding text.
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