Can I insert user-defined variables into a TOC?

[traceywaldron]

My book has a chapter-wide variable I defined called "System Heading",
and it's defined on the master page of each chapter. I want the
variable to appear in my TOC. I suppose, in retrospect, that I
should've used something more like Running H/F1,but I didn't, and now
many files are completed with this variable in use.

Question: How do I properly format and insert this "System Heading"
variable in my TOC so that it shows up? I can't find a building block
that instructs me how to handle user-defined variables.

Thanks so much for anyone's help.

-Tracey

[Tim Murray]

For next time: Never use a variable that's specific to a file. The spirit of
the variable (in a book) is to be able to distribute variables across all the
files.

Anyway, a variable (or anything else) can appear before or after the content
that's generated in the TOC, but not within it.