If you mean standard reference designations such as K for relays and such, get a copy of ANSI Y32.2-1975(IEEE Std 315-1975 & CSA Z99-1975) from Global Engineering Documents
It sounds like you are doing computer programming. If you are in the Windows world, Microsoft publishes a list of recommended variable names through their TechNet subscription program. They may offer it through other channels also. You can also check the Appendix of a number of major programming books, especially books on Access programming and sometimes C++.