Common Desktop Environment: Help System Author's and Programmer's Guide

To Create a Link to a Predefined ID

    To jump to a topic (within the same volume) that has a predefined ID, use the <link> element as shown:

<link hyperlink="id">text<\link> 

All the predefined IDs start with a _ (underscore) character. So this makes it necessary to use the hyperlink= "id" form.