Record Definition Language › RDL Field Type Descriptions › Field Types ZL and ZR — Zoned Decimal Data

Field Types ZL and ZR — Zoned Decimal Data

Field types ZL and ZR can be used to define fields which contain zoned decimal data. Type ZL defines a field containing left-justified zoned numeric data, possibly followed by 1 or more filler characters. Type ZR defines a field containing right-justified zoned numeric data, possibly preceded by 1 or more filler characters.

Valid fields must meet these conditions:

• The numeric portion must contain only digits (0–9). Commas and decimal points are not permitted.
• The value in the numeric portion must be less than 2147483648. Negative numbers are not permitted.
• The length of the field must not exceed 128 bytes.
• For ZL fields, the filler character, if any, must be blank. All-blank fields are valid, as is a field containing a single, left-justified zero, followed by all blanks.
• For ZR fields, the filler character can be either blank or zero, but not both. All-blank and all-zero fields are valid. A field containing a single, right-justified zero preceded by all blanks is valid.

Data contained in fields defined as ZL or ZR is converted to binary, bit-aligned, variable-length floating point. Blank or zero fields compress to 5 bits, while fields with a value between -16n-1 and 16n-1 compress to 5+4n bits, regardless of field length.

If invalid data is encountered in a field defined as ZL or ZR, the field is not compressed. Instead, it grows by one bit in the compressed record. No data is lost in this event; the expanded field contains exactly the same data as it did before compression. A message is printed with the statistics produced by the Compression Utility indicating the number of times invalid data was encountered in a ZL or ZR field during compression.

ZL and ZR specifications are most useful in cases where a separate type C specification cannot be dedicated to zoned numeric fields and/or multiple zoned numeric fields are not contiguous in the record. Consider an 80-byte record containing all numeric digits. The most efficient specification is C1F80. However, if 80 contiguous bytes containing zoned numerics occurred within a record for which all type C definitions were already in use, the best definition for the numeric data is 8'ZRF9',ZRF8. For zoned decimal fields of 9 bytes or less, a definition using type ZR or ZL is better than using a type C specification.