A “dummy” term, often a phrase, that is not assigned to documents when indexing, but which is inserted into the hierarchical section of some controlled vocabularies to indicate the logical basis on which a class has been divided. Node labels may also be used to group categories of related terms in the alphabetic section of a controlled vocabulary. (ANSI/NISO Z39.19-2005)

National Information Standards Organization. (2005). Guidelines for the construction, format, and management of monolingual controlled vocabularies (ANSI/NISO Z39.19-2005). Bethesda, MD: NISO Press.