I think that:
gblrst means grbl reset
gblfrh means grbl freehold
gblcyst means grbl cycle start
brlenab means grbl enable
But I have not been able to find any info on the tinyg2 forum or wiki and my attempt at debugging them was less than enlightening.
Currently my pins are floating but I would like know what state they would like to be at so that they will not cause problems in the future and so that I could potentially use them.
Any information would be greatly appreciated. Thanks!