machone,
of cause you can purchase the ATA100 specification from ATA, but there is also a list of ATA-System Codes for free aviable at <a href="http://av-info.faa.gov/dd_sublevel.asp?Folder=%5CACRef" target="_blank">AV-Info</a> either as .zip file or as a .txt file.. .I found a JASC-Code List a few weeks ago which is almost identical to ATA-100 but I can´t find it again.. .hope this one helps