Clues are the location of fabrication (korean vs Japan), type of tremolo (Edge vs Lo Trs, see tech section for pictures). Basically, if it's got an
Edge trem, it's a Japanese axe. Probably a JS-1 (which is pretty much the same as a 1000). I'm not sure, but I think the JS-100 came around in 1995.
Also, the high-end JS guitars have
Dimarzio pickups.
Hope this helps.