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.
These are:
`@' 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 for Texinfo 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 following. If you look carefully at this printed output, you will see a little more whitespace after `s.o.p.' in the second line.
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 the following. If you look carefully at this printed output, you will see a little more whitespace after the `W' in the first line.
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). This made it necessary for them to be
incompatible with some other formatting systems that use @-commands.
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 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 @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 Inserting Space.
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 @-Command Syntax, for further information.)
@dots{} (...)
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{}
Here is an ellipsis: ... Here are three periods in a row: ...
In printed output, the three periods in a row are closer together than the dots in the ellipsis.
@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 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.
@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 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 TeX:
(a + b)(a + b) = a^2 + 2ab + b^2
and 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 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.
@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 `=>' 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 `==>' 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
as `-|' 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 `error-->' 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 `==' 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 `-!-' 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
You can insert an image 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:
TeX reads the file `filename.eps' (Encapsulated PostScript
format); makeinfo uses `filename.txt' verbatim for
Info output (more or less as if it was an @example). HTML
output requires `filename.jpg'.
The optional width and height arguments specify the size to scale the image to (they are ignored for Info output). If they are both 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. This file is included in
the Texinfo distribution and is available from
ftp://ftp.tug.org/tex/epsf.tex.
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