I think Mapperz is right about PSTLSTATE, PSTZIP5, and PSTZIP4 being there to create an address locator.
I'll just add that I did some research and believe that INTSTATE is the country code, for example Canada is CA. I think the reason it's 5 characters in length is that you can get extensions like US-VI for the US Virgin Islands. Apparently it's the ISO ...
This the natural behaviour about relationship classes. It simply doesn't show the links. For example take a look at this video tutorial:
Create Many to One Relationship
As a replacement, I highly recommend Sparsx Enterprise Architecture..
Just found this, sorry if it's too late. PPDM Spatially Enabling Project didn't gain traction after Ian Batty @maguffyn and I left the project. Here's the latest update I know of http://www.oilit.com/2journal/2article/HTMLArticles/0303_15.htm
ppdm.org under Standards has PPDM Lite 1.1 and sample data for members, and I haven't looked at it for a while, but ...