Lasors 2006 Appendix A states:
Instrument Ground Time :Time during which a pilot is receiving instruction in simulated instrument flight
in synthetic training devices (STDs)
I take that to mean total Sim time with the FNPT I and FNPT II just a further break down of this...
All the other definitions which you may need are generally found in Appendix A or at the beginning of LASORS.
Hope all goes well in the un-freezing!