Hello All,

     I am looking for some clarification on Class A surface models.  I understand that Class A surface models need at least up to G3 in surface continuity.  I also understand what this means.  However I am trying to find out what G4 G5 G6 mean?  Does anyone know of some references that I could find out the different meanings of the G codes.  I am researching these for a paper and I have been hitting a wall.  Any help would be greatly appreciated.  Thanks in advance.