look up the manufacturer of the wire, for example Lincoln, and then go into the filler metals section, find that wire you are asking about and it will be in there.
By Lawrence 
Date 04-13-2010 12:11
Edited 04-13-2010 14:58
Welcome to the forum Mark
I'm going to double check my text when I get to work this morning, but I'm pretty sure the addition of "C" to the suffix is an indicator that 100% Carbon Dioxide is the prescribed shield gas for your E71T-1 FCAW electrode.
Edit:
Just double checked AWS A5.20 Specification for Carbon Steel FCAW electrodes
The "C" suffix designates Carbon Dioxide
The "M" suffix designates Mixed Gas (75-80% Argon C02 balence)
No designation means the electrode is classified as self-shielded and no external gas is used.
Some FCAW electrodes,,, for example, ESAB 710X, Hobart Fabco Hornet, and Linlcon Outershield 71M are classified under multiple designations and their operating data note both the "C" and "M" designations.
Lincoln Outershield 712C is an example of an E71T-1C that is singularly designed to run on Carbon Dioxide 100%
Last note would be to have a consern if specific impact values are required for your project as they may change with the gas mixtures vs CO2 100%... These values are often noted on the electrode manufactures specifications
