ContentIDs
ContentIDs are unique identifiers for each topic in the help file project. They can be assigned by the program or by the author. If the author assigns them, then the article cannot be submitted until the id is unque.
They can be used to link to topics inside the help file project. You do this by adding a link to a topic and with "LinkContentID=[The COntentID you want to link to]" without the []s as the link.