The engine should rev higher than normal when cold to get cat warm quicker and thus lower the emmisions. This is the function of the upshift delay.
OBD2 codes are not propietary but rather mandated by the US government. The problem is, I'd bet as Mb Doc said, Mercedes may be the only company to use this method, therefore the code is only in print with Mercedes.
ASE CERTIFIED MASTER AUTO TECHNICIAN
MERCEDES SPECIALIST 11 YRS