Processing conrefs
Except where allowed by weak constraints, a conref processor MUST NOT permit resolution of a reuse relationship that could be rendered invalid under the rules of either the reused or reusing content.
Note
When pulling content with the conref mechanism, if the referenced element is the same type as the referencing element, and the set of domains declared on the @domains attribute in the referenced topic or map instance is the same as or a subset of the domains declared in the referencing document, the element set allowed in the referenced element is guaranteed to be the same as, or a subset of, the element set allowed in the referencing element.
When pushing content with the conref mechanism, the domain checking algorithm is reversed. In this case, if the set of domains declared on the @domains attribute in the referencing topic or map instance is the same as or a subset of the domains declared in the referenced document, the element set allowed in the pushed content is guaranteed to be the same as, or a subset of, the element set allowed in the new location.
In both cases, processors resolving conrefs SHOULD tolerate specializations of valid elements and generalize elements in the pushed or pulled content fragment as needed for the resolving context.