ah yes, the old "standard weight in the manufacturers documentation wheeze". A mythical figure once seen but never again.
More seriously though, I would expect this to be the minimum equipment / lightest equipment fit required for safe flight. It may not include anything that is an option, think spats, spinner, radio, headsets, GPS, cockpit trim panels, heater, balistic chute, landing light(s) electric trimmer(s) , seat cushions, head rests, sun visors, glove box, registration decals, paint etc and then fit the narrow wheels and some thin tyres.
I bought a Rans microlight that was subsequently found to be a bit overweight because it was equally over equiped. To get it down to the legal weight I removed the following. Battery, battery box, some heavy wiring, an electric fuel pump, a brick of a GPS, about a metre of fuel pipe, fuel T pieces, sun visors, leg fairings, landing light, fire extinguisher, inner tubes from the tyres and finally, the doors as the aircraft was permitted to fly without them. I heard a rumour that the dealer kept a special light weight wooden propellor just for weighing duties but I didn't need to ask to borrow it! After the weighing I didn't bother refitting most of the stuff as the aircraft seemed to fly better without it.
How old is the aircraft? What did it weigh when originally weighed? I assume it isn't just microlights that are weighed before the issue of the first PTF/COA?