The classic C-spec packs the operation into a five-column field, so operations whose RPG IV names are longer carry truncated spellings. Each is accepted as an exact synonym of the operation it truncates:
| RPG II/III | RPG IV | Notes |
|---|---|---|
SELEC |
SELECT |
Closed by END or ENDSL; both spellings work. |
WHEQ WHNE WHLT WHLE WHGT WHGE |
WHENEQ … WHENGE |
Comparison branch under SELEC. Takes ANDxx / ORxx continuation lines exactly as WHENxx does. |
RETRN |
RETURN |
|
UPDAT |
UPDATE |
|
DELET |
DELETE |
|
DEFN |
DEFINE |
Both *LIKE and the data-area form. |
OCUR |
OCCUR |
Factor 1 sets the current occurrence; the result field receives it. |
The two spellings may be mixed freely in one program, which is what partially modernised source looks like.
*NAMVAR is the classic spelling of *DTAARA. RPG II/III writes the data-area association as *NAMVAR DEFN, RPG IV as *DTAARA DEFINE; both bind the result field to the named data area, and Factor 2 left blank defaults the data-area name to the field name.
C *NAMVAR DEFN MYDTA DA 10
C IN DA
Because RPG II/III has no D-specs, a DEFN that introduces a new field takes that field's attributes from its own field-length and decimal-position columns, following the same rule as implicit variable declaration.
Data structures on Input specifications are supported. RPG III declares data structures on I-specs (the dialect has no D-specs): a header line with DS in columns 19 - 20, followed by subfield lines with FROM/TO positions in columns 44 - 51, decimal positions in column 52, and the field name in columns 53 - 58. OCCURS (columns 44 - 47 on the header) and externally described (E in column 19) forms are both accepted. D-spec data structures are also accepted in a classic-layout source.