The Free On-line Dictionary of Computing (30 December 2018):

multiple value

    (MU) A one-to-many relationship between entries in
   a database, for example a person may have an address field
   which spanned multiple records (with different indexes).
   Multiple values are a non-relational technique.

   MUs have recently been made available in DB2, despite the
   product being so heavily influenced by Codd's Laws of
   relational databases.

   [Confirm, clarify?]

   (1995-10-30)