Maps

Two different kinds of maps are available, domain values maps (DVM) and cross-reference maps (XREF). The maps are similar in that both maps group elements by domain name and are composed of elements that map specific values from one domain to another. The difference from a technical perspective is that XREF values are constantly being created, whereas DVM values are relatively static.

XREF	DVM
Usually keys	Usually attributes
Data maintained programmatically	Data maintained manually through the user interface

Map cardinality provides an independent classification of the mapping functions. Maps are based on single values (1:1) or multivalues (N:N).