Using property process.empty.source.toc with WebHelp Classic

[opeongo]

Hi
The docbook style sheet allows table of contents to be inserted in to a document by specifying an empty <toc/> element when the 'process.empty.source.toc' property is set to 1.
I have tried this and it works for the PDF output scenario but seems to be ignored for the WebHelp Classic scenario. Is there something I am missing, or is this parameter not supported?
Thanks, Tom