EXTERNAL (Data Integrity Checking)

Function:

Checks that all external references point to Databases (DBs) of appropriate types.

Description:

The elements in some types of DB have reference or reference array attributes which can point to elements in other DBs. If the administrator uses the EXTERNAL command, the Data Integrity Checker (DICE) will check that all external references point to DBs of appropriate types. For example, a reference attribute in a Model DB which points to a Draft (PADD) DB must be illegal, but a reference attribute pointing to a Catalogue DB will be accepted.

This command cannot be used in stand-alone mode because only one DB file can be accessed at a time.

EXTERNAL NOCHECK is the default. In this mode, DICE does not cross-check any references to other DBs. This setting is used by stand-alone DICE (and REMOTE CHECK).

If EXTERNAL CHECK is specified, the following tests are applied to all external DBs to which reference is made:

• Does the referenced DB exist?

• Is the referenced DB of a valid type?

• Is the position pointed to within the limits of the referenced DB?

  Note:
  In the case of a DB which has copies, DICE only checks that the position pointed to is within the limits of the largest copy.

A non-fatal error message is produced for each invalid external reference found.

The EXTERNAL REJECT option should normally be chosen only when the administrator is certain that the DB which is being checked should not contain any external references. If this setting is used, any external reference found in the DB will be reported as a fatal error and further checking will be abandoned.

If the DICE option CHECK FILES is used, no external reference checking can be done for that file and EXTERNAL NOCHECK will be assumed.

Examples:

An example of the output when EXTERNAL CHECK is specified:

Command Syntax:

The default is NOCHECK.