The System Operator may procure the services it requires in order to balance the system either in the Balancing Mechanism, by acceptance of Bids and Offers, or via other mechanisms as deemed necessary.

Where appropriate the costs and volumes of procuring Balancing Services outside of the Balancing Mechanism are also fed through into the calculation of System Prices (SBP and SSP), in the form of Balancing Services Adjustment Data (BSAD) and also, Disaggregated BSAD (DISBSAD).

Disaggregated BSAD consists of a number of Balancing Services Adjustment Action items. Each item has an identifier (which is unique within each Settlement Period), a Volume, a Cost,SO-Flag and a STOR-Flag. For some Actions the Cost will be undefined.

National Grid ESO provides a set of adjustment actions, price and volume values for each Settlement Period.