 Better references pending.Oil companies employ specialist, independent, reserve valuation consultants - such as Gaffney, Cline & Associates, Sproule, Miller and Lents, Ltd., DeGolyer and MacNaughton, Ryder Scott, Netherland, Sewell & Associates Inc. (NSAI), Lloyd's Register (LR), Evolution Resources, Cawley, Gillespie & Associates Inc. (CG&A) and others - to provide third party reports as part of Securities and Exchange Commission (SEC) SEC filings and SPE Petroleum Resources Management System (PRMS) for other Stockmarket listings.On December 30 2009, recognising advances in exploration and valuation technology, the SEC allowed 2P probable and 3P possible reserves to be reported, along with 1P proved reserves, though oil companies also have to verify the independence of third party consultants.