The declared refinement class

This is the precise error decomposition

A one-step error of order $O(h)$ alone does not force the accumulated error to vanish. Nor does a proposed product formula automatically supply the complete-instrument estimates required here. The supplied En05-A comparison distinguishes geometry, schedule, and channel semantics CheungEn05A.

The XXI-A–C identifiers in the development plan motivate this hybrid and complete-experiment interface CheungXXIOutline. Their full texts were not supplied. The estimates used here are proved in this manuscript rather than attributed to unavailable proposition numbers.