Hello Nick,
No you are definately not the only one. I have not yet found a published comprhensive list of abreviations that lists all the abreviations and their accurate meanings.
Caravanning seems to be riddled with them, and in many cases an abreviations has become an accepted way to desribe a particular criteria, yet its actual or legal meaning may be somewhat different.
Some abbreviations in common use have no formal definition, so it is a bit of a mine field.
The PC web site does have an advice section (dark blue band) and you can look up others such as the
National Trailer & Towing Association Ltd www.NTTA.co.uk
You can also look up the Government portal for licence and vehicle weights etc.
Failing that if there is something your not sure about you can always try this forum, but be warned you are likely to get several different interpretations.