RDL Syntax Rules

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RDL Syntax Rules

Syntax rules for the Record Definition Language are as follows:

Definitions appear within Columns 1—72 of each card.
Definitions can be continued onto any number of cards.
Each field definition consists of a 1- or 2-character type code followed by a field length descriptor.
Definitions are separated by commas and/or blanks.
Groups of definitions are enclosed within quotes and preceded by a repetition factor.
Condition groups (definitions whose pertinence is dependent on record content) are enclosed in parentheses.
Numbers appearing in the language, either as field lengths or arithmetic constants, must be between 1 and 32767 (inclusive), unless otherwise specified.
Definitions are terminated with a period or by end-of-file on the RECDEF data set. Information appearing after the period is treated as a comment.

As the record definitions are processed by the Prepass Utility or the Interactive User Interface (IUI), they are checked for syntactical validity (but not applicability to the data) and printed. If syntax errors are encountered, each error is underscored by an alphanumeric character identifier, which corresponds to the initial character of an explanatory error message printed directly below the RDL statement in error.

Each RDL specification consists of a field type code and a field length descriptor. Valid field type codes and valid forms for coding field length descriptors are shown in the following tables.

The following example of the use of field definitions with length specifications has the following characteristics:

The first 8-byte field is a right-justified, zoned decimal number.
The next 100-byte field is character data.
The next 2 fields are 4-byte packed decimal numbers.
The remainder of the record is treated as character data.
```
ZRF8, C1F100, PDF4, PDF4, C1VER.
```
The following table describes valid field code types:

Field Type	Type of Data Defined
C1, C2, C3	Character data using internal frequency table 1, 2, or 3, as specified
CS	Character data using SHRVL algorithm
GA	Garbage, filler, padding, alignment bytes, and so on.
L	Insert binary length indication (for COBOL users)
MA, MB	Pattern matching
N	Exempt from compression (keys)
PD	Packed decimal data
S, X	Set of expected values
UN	Undefined field
V, VP, VZ	Variable definition
ZL, ZR	Zoned decimal, left- or right-justified, as specified

The following table describes valid field lengths descriptor codes:

Code	Description
Fn	Fixed-length field of length n, where 1<n<16384; n may contain leading zeros but may not exceed eight decimal digits.
FVS	Length determined by the previous type-V field. This descriptor is valid only for types C1, C2, C3, UN, and GA.
VER	Variable-length field extending to the end of the record. This descriptor is valid only for types C1, C2, C3, UN, and GA. This specification gives the RDL some independence from record length. In particular, the record length can be increased indefinitely without having to recreate the FDT and reimplement the data set. We strongly encourage its use.
Dc	Variable-length field delimited by a given EBCDIC character, c, or end of input record, whichever comes first. The length must be less than 128 bytes. This descriptor is valid only for types C1, C2, C3, UN, and GA. The following field definition, if any, begins beyond the delimiter.