I'll give it a try - how would I do that, I'm still new to objectscript at the moment.

Making the following change

 Property PersonIDs As list Of %String(XMLNAME = "PersonIDs", XMLPROJECTION = "ELEMENT");

Results in an error of:

ERROR #6232: Datatype validation failed for tag, PersonIDs (ending at line 9 character 15), with value:
1