BEST ANSWER
John - Arizona doesn't typically utilize a attorney review.
Nellie - Brad is correct. The standard Arizona Residential Resale contract provided by the Arizona Association of Realtors uses calendar days. The first day starts at midnight of the day the contract is signed. For example, if your contract was signed sometime on Monday, then Day 1 of the inspection period would be Tuesday.
It should be noted that this is all boilerplate language in the AAR contract. It can be overwritten, or a different contract can be used. But it should be spelled out in your contract. And your agent would definitely know.
Below is a link to a post I wrote specifically about inspection periods.
Sun Sep 14 2008, 21:10