(a) A retail installment contract may be more than one document.
(b) One of the retail installment contract documents must:
(1) provide that it applies to purchases of goods or services to be made by the retail buyer from time to time; and
(2) be signed by the retail buyer.
(c) For each purchase, the document described by Subsection (b) and a written statement relating to the purchase, including a sales slip or account book, together must set forth all of the information required by this subchapter. The document described by Subsection (a) and the written statement under this subsection are the retail installment contract.
(d) If the retail seller elects, a written statement described by Subsection (c) satisfies the statement requirements of Section 345.082 for a purchase to which the statement applies.