The object data consist of two separate pieces of information, the voltage and the measurement mode (vs Eref or vs Eoc).
The open-circuit voltage (Eoc) is a number that is applied to all Potens created from the class POTEN. When a Poten's value is used, if its flag is in the vs Eoc state, the Eoc is added to the value to get the required voltage. If its flag is in the vs Eref state, the value is used directly as the required voltage.
Therefore an operator can use a POTEN to specify either a voltage deviation from open-circuit or an absolute voltage (vs ref). To get the one from the other, use the formulae:
EvsEref = Pworking – Pref
Eoc = Pworking (at I = 0) – Pref
EvsEoc = EvsEref – Eoc
where Ps are potentials versus circuit ground.