If the file used for an externally described data structure has null-capable fields defined, the matching RPG subfields are defined to be null-capable. Similarly, if a record format has null-capable fields, a data structure defined with LIKEREC will have null-capable subfields. When a data structure has null-capable subfields, another data structure defined like that data structure using LIKEDS will also have null-capable subfields. However, using the LIKE keyword to define one field like another null-capable field does not cause the new field to be null-capable.