The only documentation that exists is regarding the implementation of external authentication, but it doesn't spell out explicit versions of supported SSO. If you are running the latest versions ALM 15.xx then the stance that Microfocus has taken is that all SAML2.0 versions of SSO are officially supported. They do not spell out explicit versions and state that if the SSO uses SAML2.0 then it is supported and compatible. If you are using an older version Such as ALM 12.6x and prior then officially the only supported version is SiteMinder and all other versions of SSO are not supported.
Whichever version of SSO that you would like to institute and the version of ALM that you are currently using or intend to move to will dictate your SSO version and whether it is officially supported or not.
Hope this helps,