The preliminary ratings assigned to the prime and nonconforming floating-rate residential mortgage-backed securities (RMBS) to be issued by Perpetual Corporate Trust Ltd. as trustee of Orion Trust 2023-1 reflect the following factors. The credit risk of the underlying collateral portfolio, which comprises 100% residential mortgage loans to residents of Australia (discussed in more detail under "Credit Assessment"), and the credit support provided to each class of notes are commensurate with the ratings assigned. Credit support is provided by subordination, and excess spread, if any. Our assessment of credit risk takes into account Brighten Financial Pty Ltd.'s underwriting standards and approval process, and its servicing quality (discussed in more detail under "Origination And Servicing"). The rated notes can meet timely payment