Let $M = (X, \mathcal{F}, \mu)$ be a D1158: Measure space.
The set of null sets in $M$ is the D11: Set
\begin{equation}
\mathsf{Null}(M) : = \{ E \in \mathcal{F} : \mu(E) = 0 \}
\end{equation}
Also known as
Set of sets of measure zero, Set of measure zero sets
