The NFIRS specification provides this definition for Relational Edit Rule 21:
Relational Edit Rule 21 — If Aid is Given (codes 3 or 4) then only the information on the Basic Module through block G1 (Resources) must be completed by the Department giving aid. The remainder of the Basic module and any other modules associated with the incident may be optionally completed but is not required. The information not captured by the Department giving aid is captured by the Department that receives aid for that incident.
Responserack’s supplement:
Responserack’s copy of the above NFIRS definition, with (when available) NFIRS codes expanded:
Relational Edit Rule 21 - If Aid Given or Received is ‘Aid Given’ (codes Mutual Aid 3, or Automatic Aid 4) then only the information on the Basic Module through Basic Module, Block G1 (Resources) must be completed by the Department giving aid. The remainder of the Basic Module and any other modules associated with the incident may be optionally completed but is not required. The information not captured by the Department giving aid is captured by the Department that receives aid for that incident.