For PHRF Lake Erie there is no penalty for sail material. So to our local PHRF, my sail fits thier definition of a class sail.
My non dacron main has the same insignia as a "class" dacron sail

For racing PHRF I don't beleive I am required to have a J/30 insignia on the sail but I am pretty sure I have to have a sail number. I don't think the number has to be of any significance other than it has to be different than everyone else that is racing in the race I enter. I have a USYRU number, some have thier hull number as thier sail number