Disability Determination Services (DDS) -- SSA's office that makes the determination whether the applicant is disabled under the Social Security law. FEDMER -- Pilot disability program between OPM and SSA; Federal Medical Evidence of Record. FERS -- Federal Employees Retirement System Statement of Participation (SOP) -- To participate in FEDMER, an employee must sign the Statement of Participation. Signing this form authorizes OPM and SSA to exchange information. Substantial Gainful Activity (SGA) -- Substantial Gainful Activity, or SGA, means that you are currently working in some capacity and receiving pay. SSA generally denies benefits based on SGA; however, pay for annual or sick leave should not result in a finding of SGA, as no significant or productive activity is being performed for this pay. For more detailed information on Substantial Gainful Activity, see the Social Security Administration's definition. SSA -- Social Security Administration TERI Cases -- "TERI" cases are disability claims in which the medical evidence shows a terminal illness. Once OPM and SSA identify a claim as involving terminal illness, they designate it as a "TERI" case, and it is expedited not only through the initial claims process, but also through any subsequent levels of appeal.