When you type in itn.com it brings up American Express - Travel. This is the itn site which is now branded as American Express.

Be sure to create a username and then go into your profile and click on "display preferences." Change "availability format" to "an expert" which will show you availability by class when you pull up a proposed flight. You can search the forum for "class codes" to see a recent posting by Wiirachay with the code explanation.