RDW

The RDW (Record Descriptor Word) parameter controls the inclusion or exclusion of the RDW for variable-length record processing. RDW permits logical access to a variable-length record without accounting for the four-byte system RDW at the beginning of each record.

The default for this parameter is set by an installation option which has an initial setting of 0(zero). Coding this parameter for a function overrides the installation-defined default setting for the duration of the job step unless a new RDW parameter is encountered.

The syntax of the RDW parameter is:

RDW=n

n

Value of 0, 1, 2, or 3, which are defined as:

0

Include the RDW during record processing and display it on output. 0 (zero) is the initial default setting

1

Include the RDW during record processing, but do not display it on output.

2

Do not include the RDW during record processing, but display it on output.

3

Do not include the RDW during record processing and do not display it on output.


Important

  • The RDW parameter must be coded before any IF, EDIT, REPL, or MOVE parameters in the control card. The RDW parameter only affects the input position, never the output location specified in a MOVE parameter. Output location 1 always refers to the first position of data.
  • When the MOVE parameter is used with a DUMP, LIST, or PRINT function, File-AID treats the function as a request to display only part of the input record. File-AID keeps track of the highest output record location used and displays an output record equal to that length. However, the RDW for variable length records is not printed for these functions when the MOVE parameter is present regardless of the setting of the RDW parameter. This option is useful when a small portion of data in a large record must be examined.

Example 1:

$$DD01 LIST RDW=3,IF=(1,EQ,C'A'),MOVE=(1,100,1)

Example 1 lists the first 100 bytes of all records of this variable-length data set that contain the character A in the first data byte of the record (not including the 4-byte system RDW). The RDW is not included during record processing as specified by the RDW parameter and is not printed since the MOVE parameter is present with the LIST function.

Example 2:

$$DD01 LIST RDW=1,IF=(5,EQ,C’A’),MOVE=(1,100,5)

Example 2 produces the same results as Example 1. The RDW setting requires the first byte of input data to be specified as 5 while the first output location is always 1. The RDW setting does not apply to output record positions during MOVE processing.

 

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