I am looking at a definition of a tensor space and came across the expression of a $\Bbb{Z}$-bilinear map in the following context:

> 
> Let $M$ and $N$ be R-module and $G$ and abelian group (i.e.
>  $\Bbb{Z}$-module). A $\Bbb{Z}$-bilinear map, $\beta:M\times N\rightarrow G$ is called $R$-balanced
>  if... *(paraphrased from Wisbauer, 1988; pg90)*
> 
> 
> 

What is the meaning of a $\Bbb{Z}$-bilinear map in this context? (p.s. I am asking about what the qualifier $\Bbb{Z}$ indicates - I know what a Bilinear map is)