Cisco Systems, Inc. Cisco Systems, Inc. Broadcom Huawei Technologies Cisco Systems, Inc. This document specifies the MPLS Network Action (MNA) Post-Stack Header encoding and procedures for carrying Network Action encodings and Ancillary Data after the MPLS label stack, based on the MNA Sub- Stack including In-Stack Network Actions and Data specified in RFC 9994. MPLS Network Actions can be used to influence packet forwarding decisions, carry additional Operations, Administration, and Maintenance information in the MPLS packet, or perform user- defined operations. This document follows the framework specified in RFC 9789. This document updates RFC 9994: the "Network Action Opcodes" registry fields, the Post-Stack MNA applicability of the opcodes, MNA scope, and Unknown action handling. This document updates RFC 9789: the definition of Readable Label Depth (RLD).