Let $M = (X, \mathcal{F})$ be a D1108: Measurable space such that

(i)	$F \subseteq X$ is a D78: Subset of $X$

The counting measure on $M$ with respect to $F$ is the D4361: Unsigned basic function \begin{equation} \mathcal{F} \to [0, \infty], \quad E \mapsto |E \cap F| \end{equation}