How do I assign one field as the description field for another field?

[Dan_DMR]

I have one field that uses numeric codes to represent road classifications and another field that has the text description of the road class represented by the number in the first field. I'd like to link the two fields such that the text field automatically fills in the description data for the numeric field to simplify labeling in map legends. In my maps I'd like to use graduated color symbology based on the numeric classification of the road but automatically be able to display the description text from the text field in the symbology. 

[BarryNorthey]

A coded value domain might get you the result you are looking for.

[MicZatorsky_AEC]

Agreed.  And by the sound of it @Dan_DMR should be able to use the codes and descriptions in his data already using a table of unique codes and then  table to domain.

[Dan_DMR]

Thanks - I've found the domain guidance from esri to be a bit advanced for me so I couldn't figure out how to set it up but I'll try following your steps and report back.