"I am just beginning to use the Survey features in Civil3D 2012 to generate a base map."
If you are just beginning, Im not quite sure why you would make such drastic changes to the OOTB Linework Codes, if you did not know what you were doing to begin with, and the consequences of those changes in other areas of the software. I would recommend using the OOTB and refine as you go along, I did things like changing the BEG to B and the END to E, (could be thinking about fbk here). But keep it simple. Not sure of the size of your shop but change to linework codes not only affect you they affect the field guys too. If you had a seasoned party chief that knew what he was doing with regards to codes, making such drastic changes could greatly effect productivity in the short term.