The type cascade (note: Type cascade) gave a note (note: Note) a type (note: Type) that neither the default profile (note: Profile) nor the project profile (9 passages, no note) declares: a source (note: Source) type, a typing rule (note: Rule) or a frontmatter (note: Frontmatter) type names a slug (4 passages, no note) that does not exist. The note is kept and treated as a document (note: Document), and its type origin records where the unknown (4 passages, no note) slug came from, so that the site (note: Site) shows it. The fix is a type of the profile (3 passages, no note), a declaration (17 passages, no note) in the project profile, or a correction (4 passages, no note) of the rule or the frontmatter.
Check (note: Check) W-TYPE-UNKNOWN, severity (note: Severity) warning 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).