I have been working for a plugin for exactly the scenario you describe...Can you clarify, from your previous post, how you envision "comments" or "explanations" would be persisted?
The plugin API made it very easy to add a new "comments" table joined to the time intervals. I'm assuming the XML webservice (via api.asp) is the primary way to interact with the database.
Here's the first problem I am facing. When I query the XML webservice, using "/FogBugz/api.asp?cmd=listIntervals&token=aqqhijlblisbv0d4pd11pdl5t0sb32" for example, I get as an XML response:
<?xml version="1.0" encoding="UTF-8"?>
It's great to see the new database table's columns returned in the XML response--the new XML elements just appear! However, no data is returned for the new table, even though valid data does exist in the database. (I'm using SQL Server) Also note that no foreign key relationship exists for ixInterval, but I'm assuming that is expected...if I end up with some orphaned comments records, that's ok.
The second problem I'm facing is editing existing comments. As far as I can tell, there are only two webservice methods I can use to access this comment data: "listIntervals" and "newInterval". How can I delete a comment, or modify an existing comment?
In case the OP (Craig HB) revisits this thread, what solution did you end up implementing?