An indicator data structure is identified by the keyword INDDS on the file description specifications. It is used to store conditioning
and response indicators passed to and from data management for a file. By
default, the indicator data structure is initialized to all zeros ('0's).
The rules for defining the data structure are:
It must not be externally described.
It can only have indicator or fixed-length character subfields.
It can be defined as a multiple occurrence data structure.
%SIZE for the data structure will return 99. For a multiple occurrence
data structure, %SIZE(ds:*ALL) will return a multiple of 99. If a length is
specified, it must be 99.
Subfields may contain arrays of indicators as long as the total length
does not exceed 99.