Data Level Descriptor

A data level descriptor is a D-pointer which defines a data section and any associated index sections. It is held in a file dictionary and is similar to a file definition item in an MD,

The format of a data level descriptor is very similar to the file definition item. Differences are as follows:

Attribute 1 X specifies that the data section will not be saved by the SAVE command.

Y specifies that the SAVE command will not save the data in the data section. An empty data section is saved and can be restored.

Note: The X and Y codes also affect FILE-SAVE and ACCOUNT-SAVE which use the SAVE command. Use of the O option in the SAVE command overrides the X and Y codes.

Attribute 2 The first value defines the location of the data section, as follows:

start, modulo, id{,scatter{,firstSplit}}

where:

start is the logical block number of the start of data section.

modulo is the modulo or, for an AFS file, the initial modulo of the data section.

id is the reuse identifier.

scatter is the number of blocks in the scatter map (scattered and AFS files).

firstSplit is the first group to be split after file creation (AFS files).

The second and subsequent values contain the same information for any indexes associated with the file.

Attribute 3 The first value is the same as for a File Definition Item, except as follows:

For a normal file on the local database the FileType is B3.
For a directory view on the local database the file creation parameters consist of the FileType (D3 in this case) and the path of the host directory.
For a special file on the local database the file creation parameters consist of the FileType (E3 in this case), the special file type and any additional parameters.
For a file on a foreign database, the file level (n) is 3.

The second and subsequent values contain the initial modulos of any indexes associated with the file.

Attribute 4 The first value contains File trigger information, as in a File Definition Item. The second and subsequent values contain the names of any indexes associated with the data section.

Attribute 13 The first value contains reallocation parameters for the data section. The second and subsequent values contain reallocation parameters for any indexes associated with the data section.

Single Level Dictionary Files

If a dictionary has no data sections associated with it (that is, it is a single level file), it contains no data level descriptors. It does, however, have a Q-pointer that points back to itself. Refer to the topic File Synonym Definition Item. A single level dictionary file can be useful if you wish to create a global dictionary to reference with the USING clause in an English statement.