As a newly hired staff auditor, you recently completed working on an audit

 As a newly hired staff auditor, you recently completed working on an audit of a publicly-held company and are now assigned to a government engagement that includes a single audit. Your supervisor asks you to familiarize yourself with OMB’s Uniform Guidance, the OMB Compliance Supplement, and the Yellow Book. What are these and why are they necessary instead of using generally accepted auditing standards like you used on your recent audit of a publicly-held company and studied in your college auditing classes?