What exactly does those FEATUREs stand for in a FME Form concurrent license file (safe.lic)? Where do I find a description / explanation?

FEATURE FME ...
FEATURE FME_GUI ...
FEATURE national ...
FEATURE basic_raster ...
FEATURE segy_reading ...
FEATURE segy_writing ...
FEATURE smallworld ...
FEATURE fmeobjects_reproject ...
FEATURE ssis_extension ...
FEATURE spatialbiz …
 

Thanks.