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A.1 @-Command Syntax
The character ‘@’ is used to start all Texinfo commands. (It has the same meaning that ‘\’ has in plain TeX.) Texinfo has four types of @-command:
- 1. Non-alphabetic commands.
These commands consist of an @ followed by a punctuation mark or other character that is not part of the Latin alphabet. Non-alphabetic commands are almost always part of the text within a paragraph. The non-alphabetic commands include
@@
,@{
,@}
,@.
,@SPACE
, most of the accent commands, and many more.- 2. Alphabetic commands that do not require arguments.
These commands start with @ followed by a word followed by a left and right- brace. These commands insert special symbols in the document; they do not take arguments. Some examples:
@dots{}
⇒ ‘…’,@equiv{}
⇒ ‘≡’,@TeX{}
⇒ ‘TeX’, and@bullet{}
⇒ ‘•’.- 3. Alphabetic commands that require arguments within braces.
These commands start with @ followed by a letter or a word, followed by an argument within braces. For example, the command
@dfn
indicates the introductory or defining use of a term; it is used as follows: ‘In Texinfo, @@-commands are @dfn{mark-up} commands.’- 4. Alphabetic commands that occupy an entire line.
These commands occupy an entire line. The line starts with @, followed by the name of the command (a word); for example,
@center
or@cindex
. If no argument is needed, the word is followed by the end of the line. If there is an argument, it is separated from the command name by a space. Braces are not used.
Whitespace following an @-command name are optional and (usually)
ignored if present. The exceptions are contexts whee whitespace is
significant, e.g., an @example
environment.
Thus, the alphabetic commands fall into classes that have different argument syntaxes. You cannot tell to which class a command belongs by the appearance of its name, but you can tell by the command’s meaning: if the command stands for a glyph, it is in class 2 and does not require an argument; if it makes sense to use the command among other text as part of a paragraph, the command is in class 3 and must be followed by an argument in braces; otherwise, it is in class 4 and uses the rest of the line as its argument.
The purpose of having a different syntax for commands of classes 3
and 4 is to make Texinfo files easier to read, and also to help
the GNU Emacs paragraph and filling commands work properly. There is
only one exception to this rule: the command @refill
, which is
always used at the end of a paragraph immediately following the final
period or other punctuation character. @refill
takes no
argument and does not require braces. @refill
never
confuses the Emacs paragraph commands because it cannot appear at the
beginning of a line. It is also no longer needed, since all
formatters now refill paragraphs automatically.
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