undecipherable (wrong?) text on def* arguments and --

[Patrice Dumas]

Hello,

There is a paragraph I do not understand (and I believe that it is 
vaguely wrong), in 'Functions and Similar Entities' in def* chapter 
in the '@deffn category name arguments...' item:

  In the unusual case when an argument name contains @samp{--}, or
  another character sequence which is treated specially
  (@pxref{Conventions}), use @code{@@var} around the argument.  This
  causes the name to be printed in slanted typewriter, instead of the
  regular slanted font, exactly as input.
  @c except for ?` and !`, but we won't explain that.

I just can't understand what is said here.

And what I understand seems to be wrong, as -- is kept as is in @def*
lines (unless I missed something), and @var do not lead to an argument
in typewriter, @code (for example) should be used for that.  But maybe I
miss a weird behaviour in @def* lines.

-- 
Pat