Create a stream whose records contain segmented string fields:

    RDO>  FOR R IN RECORD
    cont>    FOR S IN R.SS_FIELD
    cont>    PRINT S.RDB$LENGTH, S.RDB$VALUE
    cont>    END_FOR
    cont>  END_FOR

    This statement looks like a nested FOR loop.

    o  The outer loop sets up a record stream using the context
       variable R. The same context variable qualifies the field
       name, SS_FIELD, as in every FOR statement.

    o  The inner loop retrieves the segments of the string field one
       at a time.

    o  The context variable S identifies the segments.

    o  The special segmented string value expressions, RDB$VALUE and
       RDB$LENGTH are qualified by S, the context variable associated
       with the field.