I have not heard of it either.
Is this the ad
? The dry weight is 3257 and GVWR is 4652 (I noticed they had a picture of the weight sticker). Both weights seem pretty low for a 23' Shamrock comparing them to today's trailers.
I am not sure if this is an actual dry weight (such as what you would find on the yellow stickers on later models).
If it is the actual dry weight, than its the weight of the trailer as it comes from the factory with all options, but not propane, batteries, water or anything added after it left the factory.
Are you asking about the weights to figure out if you're vehicle is enough to tow?