I'm not quite sure which section asymptotics goes in, but I doubt it is calculus.

I've come across a statement from an article written in the 80s that says $\displaystyle \frac{\sigma(n)}{n\log\log n}=e^\gamma(1+\Omega_\pm ((\log n)^{-b})$ where $\displaystyle b$ is defined constant and $\displaystyle \sigma$ is the sum factors of $\displaystyle n$.

I can't seem to find anything which explains what $\displaystyle \Omega_\pm$ means...