Definition of 'hybrid" w.r.t pitching position

[Benchcoach]

It is my understanding that FED is prohibiting hybrid pitching positions while OBR and NCAA are not. The reason given for FED declaring the hybrid illegal is... "The problem is with the position (referring to the hybrid) of the pivot foot – it is engaged to the rubber, but is not entirely in contact with the rubber, nor is it parallel to the rubber. Of course, while the high school (FED) rule book uses the word "parallel" in defining the set position, neither OBR nor NCAA rules use that word."