Project Maturity Sub-Class of a development on hold project is defined as resources in a proven field (namely, a field that has been drilled and in which a discovery has been made according to the rules of PRMS), but for which the activities have been put on hold and/or for which the economic justification to develop the field could be significantly delayed.

The conditions to define these resources (all or part) as reserves, are the approval of a development plan and proof that the development of the field and production from it are economic.