thinking the thoughts over a jamaica numba one, page-25

"P" indicates reserves while "C" indicates contingent resources:

http://www.world-petroleum.org/publications/Petroleum%20Resources%20Classification%20System%20and%20Definitionsdoc2.doc

"RESERVES. Reserves are defined as those quantities of petroleum which are anticipated to be commercially recovered from known accumulations from a given date forward.

"CONTINGENT RESOURCES. Contingent Resources are those quantities of petroleum which are estimated, on a given date, to be potentially recoverable from known accumulations, but which are not currently considered to be commercially recoverable.

The prefix 1, 2 or 3 refers to low estimate, best estimate or high estimate, respectively, or numerically 90%, 50% or 10% confidence levels. With reserves, this is also called Proven, Proven & Probable and Proven, Probable and Possible.