This module defines the textual conventions for Cisco Network Admission Control(NAC) system. The Cisco Network Admission Control security solution offers a systems approach to customers for ensuring endpoint device compliancy and vulnerability checks prior to production access to the network. Cisco refers to these compliancy checks as posture validations. The intent of this systems approach is to prevent the spread of works, viruses, and rogue applications across the network. This systems approach requires integration with third party end point security applications, as well as endpoint security servers. Terminology used: EOU - Extensible Authentication Protocol over UDP. UCT - Un Conditional Transition. CTA - Cisco Trust Agent. EAP - Extensible Authentication Protocol. An extension to PPP. ACS/AAA - Cisco Secure Access Control Server. The primary authorization server that is the network policy decision point and is extended to support posture validation. NAD - Network Access Device that enforces network access control policies through layer 2 or layer 3 challenge-responses with a network enabled Endpoint device.