(a) Contract means an enforceable agreement entered into between the authority and a contractor.

(b) Contractor means any person, partnership, private corporation or association: (1) selling materials, equipment or supplies or leasing property or equipment to the authority; (2) constructing, reconstructing, rehabilitating or repairing buildings, highways or other improvements for or on behalf of the authority; or (3) rendering or providing services to the authority pursuant to a contract.

(c) Designated payment office means the office designated by the authority to which a proper invoice is to be submitted by a contractor.

(d) Proper invoice means a written request for a contract payment that is submitted by a contractor to the authority's designated payment office setting forth the description, price and quantity of goods, property or services delivered or rendered in accordance with the terms of the contract, in such form and supported by such other substantiating documentation as the authority may reasonably require.

(e) Receipt of an invoice and invoice received datemean the later of: (1) the date on which a proper invoice is actually received in the designated payment office; or (2) the date on which the authority receives the purchased goods, property or services covered by the proper invoice which, with regard to final payments on construction contracts, shall mean the date on which all the contract work has been accepted as completed by the authority in accordance with the contract terms.

(f) Setoff means the reduction by the authority of a payment due a contractor by an amount equal to the amount of an unpaid legally enforceable debt owed by the contractor to the authority.