Do $\{x\mid x\in\mathbb{R},xShort question about set-builder notation.

Do 
  $$D=\{x \mid x \in \mathbb{R}, x < k\}$$
  and 
  $$D=\{x \in \mathbb{R} \mid x < k\}$$ 
  mean the same thing?

I see both of them used in different contexts and was wondering if they are interchangeable. 

They mean the same thing. I prefer $\{x \in \mathbb{R} \mid x < k \}$, because it is a clear separation between the domain ($\mathbb{R}$) and the condition ($x < k$). So I think it is easier to read, definitely when the condition gets more complicated.
