static hold questions

I've seen this list, and I'm tried a few guesses as to what I think they are but could I get some clarification?

60 sec plank

60 sec reverse plank

60 sec arch hold

60 sec hollow hold

are the plank and reverse plank done on the ground? Or is this with legs elevated using rings? Or some other way?

My assumption is locking the elbows on the ground and toes then keep mid section and legs straight, stomach facing floor.

Reverse, my assumption is hands below body, stomach side up, body/legs straight.

For the Arch, stomach on ground, raise legs and arms up.

For the hollow, back on ground, raise legs and arms up.

You got them right on all accounts

Plank and reverse plank should be with body parallel to the ground eventually, but you can start on the floor if you can't do at least 15-20s horizontally.