All objects in a DCM database are automatically assigned special properties. Some of these properties are: Local To, From, Modifiable In, and Work in DB. DCM uses these traits to preserve the uniqueness and histories of all objects in a DCM cluster. The properties are described as follows:
The value of the Local To property (the local_to attribute) is the database ID of the database in which the first version of the object was created. All versions checked out from that initial version Receive the same value of the Local To property.
The value of the From property (the created_in attribute) is the database ID of the database in which that specific version was created or checked out.
Modifiable In or Work in DB- The value of the Modifiable In property (the modifiable_in attribute) is the ID of the database that controls the object. DCM allows a specific object to be modified in one database only in the DCM cluster. In all other databases, that object cannot be modified, except for moving it to later states. If the Modifiable In property does not exist, then the controlling database is determined by the From (created_in) property. Typically, files, directories, and projects do not have a Modifiable In property by default.
The figure shows a Rational Synergy Class History of an object called main.c. It was first created in the Boston database. Therefore, the Local To and From values for the first version (main.c-1) are both set to the ID of the Boston database (MA). When main.c is checked out from the Chicago database, the From value is set to the ID of the Chicago database (IL). When main.c is checked out from the Boston database, the From value is set to the ID of the Boston database (MA). As shown in the figure, the Local To value never changes during the entire history of an object.
In addition to these properties, all DCM objects are assigned attributes that ensure their uniqueness. For example, each object version is linked to a unique cluster ID. These object traits provide security features that: