The specification of structures offers the following options for input compression:
STRUCTURE-IMPLICIT notation
Specification of the structure-initiating operand is omitted and the subordinate operand is entered outside the structure parentheses. The prerequisite for this is generally that the subordinate operand is unique with respect to the entire command/statement or to a higher ranking structure. Operands for which the STRUCTURE-IMPLICIT notation is guaranteed in the long term are listed explicitly in the corresponding command or statement description.
Example
SHOW-FILE-ATTR ACCESS-METHOD=*ISAM
is the abbreviated notation for
SHOW-FILE-ATTR SEL=*BY-ATTR(ACCESS-METHOD=*ISAM)
Note
In many cases in which the STRUCTURE-IMPLICIT notation is not possible, “flat notation” as outlined below can be used.
Flat notation
The structure-initiating operand is specified. The subordinate operand, however, is entered outside the structure parentheses. The subordinate operand need not be unique with respect to the entire command/statement. It must not occur in more than one active structure. Note that a structure is activated not only explicitly but also implicitly via the default value, if an operand specification is omitted.
Flat notation is not guaranteed on a long-term basis.
Example
CRE-FILE FILE1,SUP=*PRIV-DISK,VOL=ABC123,DEV-TYPE=D3435
is the abbreviated notation for
CRE-FILE FILE1,SUP=*PRIV-DISK(VOL=ABC123,DEV-TYPE=D3435)
Notation if NULL-ABBREVIATION=YES
The subordinate operand is entered within the structure parentheses, but the structure initiating operand value is reduced to a null string, i.e. omitted. The prerequisite for this is that the structure-initiating operand value has been defined with the attribute NULL-ABBREVIATION=YES in the syntax file. This attribute can be assigned only once within the set of possible operand values (if several structure-initiating operands are admitted; see the “SDF-A” manual [33]).
In the syntax representation, operand values for which the attribute NULL-ABBREVIATION is guaranteed on a long-term basis are enclosed in square brackets (see "SDF syntax representation").
Example
MOD-FILE-ATTR FILE1,PROTECTION=(ACCESS=*READ)
is the abbreviated notation for
MOD-FILE-ATTR FILE1,PROTECTION=*PARAMETERS(ACCESS=*READ)