From the Federal Register - U.S. government (eff. July 25, 2012)

Social Security Ruling, SSR 12-2p; Titles II and XVI: Evaluation of Fibromyalgia
  Notice issued by the Commissioner of Social Security on the Ruling (SSR 12-2p) providing guidance for evidence that needs to be met in order to establish that a person has a medically determinable impairment of Fibromyalgia (FM). It also reviews the evaluation of FM in disability claims/continuing disability reviews under Titles II and XVI of the Social Security Act. Effective date of this ruling: July 25, 2012.