Mapping is the process of connecting a global variable name to a database file.

A complete mapping has the following four components:

These components may be defined in any order, but the final result must be a complete logical path from name to file:

NAME(s) ---> REGION ---> SEGMENT ---> FILE

The default Global Directory contains one complete mapping that comprises these entries for name, region, segment, and file.

* ---> DEFAULT ---> DEFAULT ---> mumps.dat
(NAME) (REGION) (SEGMENT) (FILE)

The * wildcard identifies all possible global names. Subsequent edits create entries for individual global names or name prefixes.

Regions and segments store information used to control the creation of the file. The characteristics stored with the region and segment are passed to MUPIP only when creating the database file using the CREATE command, so subsequent changes to these characteristics in the Global Directory have no effect on an existing database.

When you create a new mapping, GDE ensures that it has all these components by refusing to complete the EXIT command until all components of the mapping exist. Informational messages inform you of any missing or extra components.