In mfg. plant, are all outlets to be labeled for identification?

[John Harrison]

Outlets are not required to be labled for identification although it would be nice to have done. Aside from 110 outlet, 220 outlet ect.. what other labeling would you need on an outlet. Unless you are dedicating an outlet to a specific piece of equipment such as Drill press ect. All breakers need to be labeled for identification.