Doubts in pcells

 Hi all,

          I have library with full of pcells(every cell had views like spectre, symbol, ivpcell, hspiceD,layout,ams,auLvs....etc). These are not created by pcell option in layout. And techfile doesnot contain "Opus Symbolic Device Class Definition" . But these cells act as pcells. Let me know how is it possible?

          Can any body explain function of  spectre, symbol, ivpcell, hspiceD,layout,ams,auLvs,auCd1...?

   Thank you.