Three types of SSA’s we can see in IMSDB:
Unqualified SSA. This only specifies the SEGMENT TYPE the program is interested in. Here you don’t indicate a particular occurrence of a segment because you don’t care which occurrence of a segment you get.
The segment name is first eight characters padded by space up to the ninth position instead of a left parenthesis.
For example – HOSPITALb. This will retrieve the first occurrence of HOSPITAL segment. Here ‘b’ is blank at ninth position.
Qualified SSA. This is addition to the SEGMENT TYPE, also contains one or more qualification statements.
A qualified SSA describes the segment occurrence a program wants to access. This description is called a qualification statement having 3 parts.
A qualified statement is enclosed in parenthesis. The part names the field that DL/I will use for segment search.
The second part names the Relational Operator of two bytes telling DL/I what kind of comparison to make during the search. The third part is a variable length field that contains the values for comparison during DL/I search. **Can code more than one qualification statement.
Fully Qualified SSA The SSA’s give complete information about each segment occurrence in the search hierarchy path.
In the ninth position of SSA:
- A BLANK indicates unqualified SSA
- A LEFT PARENTHESIS indicates qualified SSA
- An ASTERISK indicates one or more command codes