MMP.17:4.6 - Carry the substitution into continued use

Make the evaluation rule, input meanings and region, selected responses, and consequential limits available with the replacement. The receiver must be able to obtain its response and recognize when the fallback applies. A function with its conditions in the surrounding model may suffice.

When the surrogate enters an inverse problem or an uncertainty calculation, propagate its approximation in the observation metric and into the requested conclusion. A small forward-response error can matter greatly along a poorly resolved direction. MMP.12 supplies the ambiguity and regularization analysis; MMP.13 supplies the qualified inference and uncertainty. Treating the replacement as an exact likelihood or forward relation can give a tighter answer than its construction supports.

Reopen the construction when the input region, source assumptions or receiving operation changes. A new question about an intervention may need causal identification or a mechanism supplied by the subject practice, even if the old predictions remain accurate. A new request for explanation needs the relevant relations, not only the same output number. Use C.2.8 to distinguish the structure a reader can recover and EXD to construct an explanation from a supplied subject account. A compact surrogate may expose useful structure, but compactness and predictive fit do not establish that contribution.