ax

We're working to support several IdP's as a relying party. Some of the IdP's we want to collect data from use sreg for data exchange and some use each flavor of AX (axschema.org and schemas.openid.net). Does anyone have guidance on how to determine the format that a given provider uses, preferably programmatically, so that we're not filling the request with key=values which will not be acknowledged?

On the subject of AX, is axschema.org dead? From what I understand it's the most common AX schema used but it appears the site is gone from the internet.