" There were two main reasons that the name of this condition was changed from multiple was changed from multiple personality disorder to DID in the DSM-IV. The first was that the older term emphasized the concept of various personalities (as though different people inhabited the same body), whereas the current view is that DID patients experience a failure in the integration of aspects of their personality into a complex and multifaceted integrated identity.
The International Society for the Study of Dissociation (1997) states it this way: "The DID patient is a single person who experiences himself/herself as having separate parts of the mind that function with some autonomy. The patient is not a collection of separate people sharing the same body." ͏ "
― , Handbook of Psychology, Volume 8: Clinical Psychology