Never hesitate to ask directly
Please remember that the GAO has no authority over you AND they are very, very nice. First, they put the standard on the internet both in an Adobe format and in a text format. This makes it imminently readable and usable.
But most importantly, the GAO pays for someone to answer our questions! The gentleman who answers questions about the Yellow Book when you write to email@example.com  - Michael C. Hrapsky - is so cool and generous, you won’t believe it! Once I called him to ask a question about an obscure paragraph in the Yellow Book and he asked around his office to find out what I wanted to know. Turns out, they decided to delete the offending paragraph from the 2006 revision. He isn’t defensive – he is collaborative. He never shames you for asking a silly question - and I've asked so many he called me one of his 'clients' once...
He gets right back to you when you call or email. It is a DREAM talking to him. Why can’t the AICPA or the IIA be like that? I feel like giving the GAO a hug.