A declared relation (note: Relation) joins two types (note: Type) the profile (note: Profile) does not allow for it. The link (note: Link) is dropped from the model (note: Model) by the relation typing (note: Relation typing) step (note: Step). A frontmatter reference (note: Frontmatter reference) that names an existing note (note: Note) of a type the attribute (note: Attribute) does not accept is this finding (note: Finding), not an unresolved reference (note: Unresolved reference): the note exists, the relation is what the profile forbids.
Check (note: Check) E-META-REL, severity (note: Severity) error (29 passages, no note) by default, documented with a before and after example in the check pages. The severity can be overridden per project (note: Project) or per repository (note: Knowledge repository).