grober
MB Master
For those fortunate enough [or just merely curious] to have access to Mercdes EPC [ electronic parts catalogue] either through Mercedes-Benz Club membership or via bootlegged or official DVD's here's a well illustrated "how to to use " pdf online.
http://bayhas.com/mercedes/EPC manual/EPC instructions.pdf
http://bayhas.com/mercedes/EPC manual/EPC instructions.pdf