List of supported attributes in IAM Identity Center

AWS provided an official document which lists out the supported attributes of in IAM Identity Center (AWS SSO) (Under section: Supported IAM Identity Center attributes)

However I found that the list is incompleted. For example ${user:employeeid} is not in the list but still can be mapped and returned in SAML assertion.

My question is: Is there a list or command can listed out all the supported attributes when using **Identity Center directory ** as source? I would like to use other attributes like User Type in the user profile.

Thanks, Ray