Inside a region delineated by @iftex and @end iftex,
you can embed some plain TeX commands. Info will ignore these
commands since they are only in that part of the file which is seen by
TeX. You can write the TeX commands as you would write them in
a normal TeX file, except that you must replace the `\' used
by TeX with an `@'. For example, in the @titlepage
section of a Texinfo file, you can use the TeX command
@vskip to format the copyright page. (The @titlepage
command causes Info to ignore the region automatically, as it does
with the @iftex command.)
However, many features of plain TeX will not work, as they are overridden by features of Texinfo.
You can enter plain TeX completely, and use `\' in the TeX
commands, by delineating a region with the @tex and @end
tex commands. (The @tex command also causes Info to ignore the
region, like the @iftex
command.)
For example, here is a mathematical expression written in plain TeX:
@tex
$$ \chi^2 = \sum_{i=1}^N
\left (y_i - (a + b x_i)
\over \sigma_i\right)^2 $$
@end tex
The output of this example will appear only in a printed manual. If you are reading this in Info, you will not see anything after this paragraph. In a printed manual, the above expression looks like this:
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