Hi Belg,
0n30 is the scale I am into, not 0n3 which is slightly different again in track width.
It is 0 gauge running on H0 gauge track but the ties are wider apart. My track is 0-16.5.
The 30 stands for 30" gauge or as Model Railroader say's 2.5 meaning 2'-6" (Which is 30" anyway)
Shamus