In Schedule A of the Delegations Rule, each delegation is coded G1-G4, S1-S5 or NT1-NT2.
The code determines whether anybody else besides the specified delegate can exercise the delegation as per the Delegations Rule, visually represented as follows (please right click on image to download a copy to your hard drive):
G4 - Heads of Work Unit for delegations purposes are defined in Schedule B of the Delegations Rule.
Generalist and Specialist Delegations held by the least senior delegate are held also by that delegate's immediate supervisor or line manager and successively by each subsequent supervisor or line manager within the chain of delegation up to the Council. If a supervisor or line manager wishes to exercise a delegation held by a delegate, he or she can do so but it must be before the delegate exercises his or her delegation and only in special circumstances.