Check-Code and Mode-Check

On the other hand, if all the fields are known then it can be verified whether the relationship holds for the given predicate. This verification can be done by running appropriate piece of code known as check-code C. A check-code C for a predicate P is evaluable if and only if its mode ${\cal M}_c$, known as mode-check, is satisfied. The mode ${\cal M}_c$ is a collection of fields that comprise the relationship $\mathbb{R}$. Evaluation of check-code ${\it eval}_c$ can be seen as a mapping

${\it eval}_c$ : C $\rightarrow$ $\mathbb{B}$