Scook Sorry, found vst2 just now, finally (i use Studio One v2, 64bit), but for appear vst2 in list i had to be removed (rename the extension) of vst3 z3ta file - without this, host did not want scan vst2 dll, strange.
Just usually i shoose vst2 for use in most plugins, because vst3 is still buggy or has random restrictions in many cases, i dont know why.
For example, in the first minute of the test vst3 of z3ta i noticed that in Mod.matrix the range levels just not automatable for host (not transmit their levels to daw) - what transmit absolutely properly in vst2 (i cheked).
Who knows what else is not working in vst3 ? So, for just in case..