Texinfo has commands for indicating just what kind of object a piece of
text refers to. For example, metasyntactic variables are marked by
@var, and code by @code. Since the pieces of text are
labelled by commands that tell what kind of object they are, it is easy
to change the way the Texinfo formatters prepare such text. (Texinfo is
an intentional formatting language rather than a typesetting
formatting language.)
For example, in a printed manual,
code is usually illustrated in a typewriter font;
@code tells TeX to typeset this text in this font. But it
would be easy to change the way TeX highlights code to use another
font, and this change would not effect how keystroke examples are
highlighted. If straight typesetting commands were used in the body
of the file and you wanted to make a change, you would need to check
every single occurrence to make sure that you were changing code and
not something else that should not be changed.