There is a long discussion on the CWOP mail list going on now. It has some interesting reading on why some things are done in CWOP/findU.
Go here and read the (wxqc] Field order in CWOP records) messages. If it is too boring or hard to follow just read the entries from Russ Chadwick, Philip Gladstone, and Steve Dimse. These guys are pretty much the guys that made the CWOP network and there are some very interesting explanations of why things are as they are being given out.
http://server.gladstonefamily.net/pipermail/wxqc/2014-February/date.html