The ratings assigned to the prime floating-rate residential mortgage-backed securities (RMBS) issued by Perpetual Corporate Trust Ltd. as trustee of the IDOL 2017-1 Trust reflect the following factors. The credit risk of the underlying collateral portfolio (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 lenders' mortgage insurance (LMI) cover. The assessment of credit risk takes into account the underwriting standards and approval process of ING Bank (Australia) Ltd. (ING Bank Australia), which are consistent with industry-wide practices; the servicing quality of ING Bank Australia (discussed in more detail under "Origination And Servicing"); and the support provided by the