A.19.SOURCE-SET-SPACE-SUBSTRATE:10 - Rationale
The pattern chooses a narrow but sturdy center of gravity.
A.19 already declares CharacteristicSpace. The missing load is not another free-floating space kind. It is the ref-position and relation stack that tells the reader:
- which declared source set is active;
- which declared space is named in the search-side position;
- which declared space is named in the outcome-side position;
- what
SpaceRefRelationKindsays about those two refs; - and how much transparency, distortion, uncertainty, or error the line is honestly claiming.
That is why this pattern stops before interpretive views and before publication metadata. If it tried to say less, the load would collapse back into vague space or projection talk. If it tried to say more, it would start absorbing views, fronts, archives, shortlists, or shipping semantics that belong elsewhere.