Attributes, behaviours, user lists, the default propagation handlers, colour and
merge-region attributes and ReadIndexedAttributesFromDB, with the SmAObject
attribute-list calls co-ported into AttributeStore. Merge on merge-region
attributes is UNPORTED(topology.shell). difftest: 2029 cases, 1991 pass, 38
deferred, max_rel_err 0.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>