Does the calculation period always have to be on a 12-months basis?

For example if a plant has scheduled turnaround periods or unscheduled production-stops (force majeure), can certain months only be considered for the calculation?

The calculation period should cover a full twelve-month period and it must be as up to date as possible. In cases of exceptional maintenance measures and unstable production conditions a shorter period (for inputs and respective outputs) may be considered if it better reflects the relevant timeframe. If these activities reflect the normal production process of a year these have to be considered and included in the calculation and twelve months have to be considered.The respective period for data gathering and thus for the calculation of GHG emissions must be transparently displayed in the calculation.