Defining a physical file using DDS

You use file-level, record-level, field-level, and key-field-level entries to define a physical file with data description specifications (DDS).

A physical file can contain only one record format. To define a physical file, follow these steps:

Specify the record format in either of the following two ways:
- Define a new record format.
  Specify field and key-field specifications as required for the new record format.
- Share an existing record format.
  Use the FORMAT keyword to specify that the operating system is to use a previously defined record format from another physical file. When the FORMAT keyword is used, you must specify key-field level specifications again (if a keyed access path is required) even if they were specified on the existing record format.
Specify the entries in the following order to define a physical file:
1. File-level entries
2. Record-level entries
3. Field-level entries
4. Key field-level entries

Note: The file name is specified through the Create Physical File (CRTPF) command, not through DDS.

The maximum number of fields in a record format is 8000. If any of the fields in the record format are date, time, timestamp, variable length, or allows the null value, then the actual maximum number of fields can be less than 8000. The maximum number of fields can vary depending on the number of fields and combinations of fields that occur within the record format. The maximum number of bytes in a record format is 32 766 if variable length fields are not included and 32 740 if variable length fields are included.