@|: Literal vertical bar, or optional line break

In the TeX (documentation) part of a section, @| inserts a vertical bar. Here's a LaTeX example:

     \begin{verbatim}
       The constructions @|x@| and |x| are very different.
     \end{verbatim}
     

You might wish to try this out to see what FWEAVE produces.

In a code part, @| inserts an optional line break in an expression.