OPM System Attributes for Versions

Version information is represented using the following system attributes:

1. (non-versioned) version system attribute for an instance
   1. _defaultVersion (with data type INTEGER) indicates the current version number of an object instance; null means that there is no default (or current) version;

   2. _nextVersion (with data type INTEGER) indicates the next version number for a new version;

2. (versioned) version system attributes for a version
   1. _version (with data type INTEGER) represents the version number of an object;

   2. _preVersion (with data type INTEGER) represents the version number preceding this version;

   3. _fromDate (with data type DATETIME) represents the time this version is created;

   4. _deleteDate (with data type DATETIME) represents the time this version is logically deleted (or expired).

All of the above system attributes are single-valued. Attributes nextVersion, _version and _fromDate are also specified with minimum cardinality of 1.

Additional version attributes can be computed using methods:

1. _sucVersion represents the version number(s) succeeding a specific version; this attribute consists of all versions with the same _oid and _preVersion equal to this specific version number;

2. _lastVersion represents the last used version number of an object instance; this attribute value is computed as: _nextVersion - 1.