The methodology was explained in detail in the most recent...

The methodology was explained in detail in the most recent update Tuesday 26th Feb.
"The PCD has demonstrated commercial gas production from 1 of 3 coal seams located within the Telford basin and there is additional opportunity for resource upgrades in the future. The Company expects to realise a significant reserve large enough to support a commercial project of over 20 years. Thereafter, LCK expects that additional resources will be upgraded as the project progresses."

i.e. 1 out of 3 coal seams will be upgraded initially, which should be sufficient to support commercial operations. The other 2 will be bonuses for teh future.