Directly from the SBA's website here, this is the Paycheck Protection Program Interim Final Rule and contains additional eligibility criteria and requirements for certain pledges of loans. The guidance can be found at https://www.sba.gov/sites/default/files/2020-04/Interim-Final-Rule-Additional-Eligibility-Criteria-and-Requirements-for-Certain-Pledges-of-Loans.pdf.