Common PKI V.1.1 already comprises some guidance on authentication certificates. But with the growing interest in this field the Common PKI board became more and more aware of the fac that a number of problems and questions around authentication and autorisation have to be clarified to promote interoperability. The intention of the present paper is to provide an authentication certificate profile that can be used in many system environments and in many widely used applications. The paper is now published as a stand-alone document. As such it can still be regarded as work in progress. Further discussion and comments are desired.