(i) | $\text{MS} = \text{MS}(X \to [0, \infty])$ is the D2958: Set of measurable simple functions on $M$ |

(ii) | $f : X \to [0, \infty]$ is a D313: Measurable function on $M$ |

**unsigned basic integral**of $f$ with respect to $M$ is the D5237: Unsigned basic number \begin{equation} \int_X f \, d \mu : = \sup_{\phi \in \text{MS} : 0 \leq \phi \leq f} \int_X \phi \, d \mu \end{equation}