Map IDs for Bookmarks

Hi,

I have inherited a Help file that has map IDs pointing to different sections of the same topic. It is as if bookmarks were used rather than topics for the map IDs. (The Preferences dialog box, which has 3 tabs, is documented in one topic. Each tab has its own help icon, which then jumps to the relevant section in the topic.)

I didn't know that this was possible. Does anyone know how it is done?

Thanks,
Jackie