IDMSRSTT Macro Statements › IDMSRSTT FIELD › IDMSRSTT FIELD Usage

IDMSRSTT FIELD Usage

Contiguous fields

If a contiguous group of fields remains contiguous and internally unchanged in all occurrences, it can be treated as if it were a single field. Therefore, field-length, old-displacement, and new-displacement can refer to the entire group.

If any part of the group is changed, or occurring multiply without maintaining the same relationship with the rest of the group, then it must be treated separately.

Accounting for all data fields

The IDMSRSTT FIELD statements you code for a record must account for all the data fields in the record:

• If you are adding, modifying, or deleting any data fields in the record, or if the control field of the record is changing, code one IDMSRSTT FIELD statement for each field or group of contiguous fields in the record.
• If you are not adding, modifying, or deleting any data fields in the record, and the control length of the record is not changing, code a single IDMSRSTT FIELD=ALL statement.

Calculating data field positions

The first byte of data in a record is at location 1. When calculating field positions for variable-length records, do not count the 4-byte variable-length indicator maintained at the beginning of the data portion.

Specifying new field values

The value for new-field-value is expressed as an Assembler constant (for example, CL2' ', indicating a 2-byte field initialized to spaces).

For new fields that have not been assigned an initial value in the new schema, IDMSRSTC supplies an initial value based on the usage specification in the schema, as follows:

X is the length, in bytes, of the field.

Expansion to the right of a decimal point

The restructure utility as a general rule cannot expand a field to the right of a decimal point. To do this, the standard procedure would be to first add the needed bytes to the left of the field. After the RESTRUCTURE has been performed, a user-written program must modify each affected record by multiplying the expanded fields by the proper factor to realign the decimal point to the new position.