Accessible data items usually require that certain representations of data be stored. File connectors require that certain information concerning files be stored. The storage associated with a data item or a file connector can be external or internal.
External and internal items can have either global or local names.
A data record described in the Working-Storage Section is given the external attribute by the presence of the EXTERNAL clause in its data description entry. Any data item described by a data description entry subordinate to an entry describing an external record also attains the external attribute. If a record or data item does not have the external attribute, it is internal.
A file connector is given the external attribute by the presence of the EXTERNAL clause in the associated file description entry. If the file connector does not have the external attribute, it is internal.
The data records described subordinate to a file description entry which does not contain the EXTERNAL clause or a sort-merge file description entry, as well as any data items described subordinate to the data description entries for such records, are always internal. If the EXTERNAL clause is included in the file description entry, the data records and the data items attain the external attribute.
Data records, subordinate data items, and various associated control information described in the Local-Storage, Linkage, Report and Screen Sections are always internal. Special considerations apply to data described in the Linkage Section whereby an association is made between the data records described and other data items accessible to other run-time system elements.
If a data item or file connector is external, the storage associated with that item is associated with the run unit rather than with any particular run-time system module within the run unit. An external item can be referenced by any run-time system module in the run unit that describes it. References to external items from different run-time system modules using separate descriptions of the data item or file connector are always to the same item. In a run unit, there is only one representation of an external item.
If a data item or file connector is internal, the storage associated with it is associated only with the run-time system module that describes it.