105 Mental Health Residential Treatment Center means a facility that meets all of the tests of the Acute Care Hospital definition or that is licensed in accordance with the laws of the appropriate legally authorized agency as a residential treatment center for Mental Health Services . Nurse means only a person who is a registered Nurse (R.N.), a licensed vocational Nurse (L.V.N.), or a licensed practical Nurse (L.P.N.). Partial Hospitalization Care means only continuous treatment of substance abuse or of a mental, nervous or emotional disorder or condition for at least 4 hours, but not m ore than 12 hours, in an y 24 - hou r period. Participant means a person who is eligibl e for benefits under the Plan. Participation Agreement means the agreement providi ng for coverage under the Plan. Payment Percentage means the percentage the Plan pays of a covered medical charge after any applicable deductible is satisfied. Physician means a doctor of medicine or a doctor of osteopathy who is licensed by his jurisdiction and acting within the scope of his license to practice medicine or to perform surgery. Plan means the National I AM Benefit Trust Fund. Preferred Provider Organization means an organization that negotiates discounted rates with medical providers in an effort to provide benefits to participant s. Preferred Provider means a provider that enters into an agreement with the Preferred Provider Organization to provide service s at negotiated discount rates. Pregnancy means any Pregnancy, a complication thereof, or the termination of a Pregnancy. Pregnancy benefits are payable on the same basis as benefits for treatment of an illness . Professionally Recognized Standards means professionally recognized standards of quality, as determined by the Trustees, or their delegates. To determine such standards, the Fund Office may use such groups as: The Amer ican Medical Association; The American Dental Association; their affiliates and successors; peer review groups; professional rev iew groups; and similar groups. Retiree means a person who formerly qualified as an Employee, who has retired from active employ ment while covered by this Plan, and on whose behalf the Employer continues to make the required contributions to the Plan, but only if the particular coll ective bargaining agreement or p articipation a greement allow for Retiree coverage. Skilled Nursing F acility and Rehabilitation Hospital each mean only an institution that meets all of the following tests: • It mainly provides skilled nursing care or rehabilitation care to registered inpatients; • It provides care that is supervised, 24 hours per day, by a ph ysician or registered Nurse; • It has available at all times a physician who is a staff member of an Acute Care Hospital; • It has a registered Nurse, licensed vocational Nurse, or licensed practical Nurse on duty 24 hours per day and has a registered Nurse on duty at least eight hours per day; • It maintains a daily medical record for each patient; • It complies with all licensing and other legal requirements; • It is not a Specialized Facility; and