Algebra definitioin (please help)

[techn0scho0lbus]

I'm stranded in a foreign country without a textbook.
Does anyone happen to know the definition of this:
"R\{0}" for Ring, R and 0 is likely the addative identity.

Here is some context:
R is a field iff R is commutative and R* (the group of units of R) = R\{0}.

I would appreciate any help,

Thanks!!

P.S. the slash might go the other way too (i.e. R/{0}). If you know for sure which way it's suppose to go, please let me know.

 

[techn0scho0lbus]

Update:

I now think it means "the ring R without 0" or "R with the addative identity factored out."

 

[pka]

I now think it means "the ring R without 0" or "R with the addative identity factored out."

The "" is known as setminus in TeX.
\(\displaystyle A\setminus B = A \cap B^c .\)