What are the minimum floatation requirements so that issuer/security becomes eligible for shelf registration rule?

Can some one explain : What are the minimum floatation requirements so that issuer/security becomes eligible for shelf registration rule? Not sure if this is part of L3 or anyother curriculum but came across it as a requirement to qualify for rule 415 (shelf registration rule)

not sure, but think it has to do with the commision you pay bankers for when you go public? That’s what comes to mind when I think flotation requirements.

So are there any guide lines on flotation costs such as % of security value etc etc ? I thought it was one of the items in the negotiation/other types of bids.Tried to go thru SEC website and got lost…Any way thanks