Restrictions on Subscripting

  1. A data-name must not be subscripted or indexed when it is being used as a subscript or qualifier.
  2. An index may be modified only by a PERFORM, SEARCH, or SET statement.
  3. When a literal is used in a subscript, it must be a positive or unsigned integer.
  4. When a literal is used in relative subscripting and indexing, it must be an unsigned integer.