Huawei Huawei China Mobile China Mobile Orange This document defines a method to tag nodes that are associated with operation and management data in YANG modules. This method for tagging YANG nodes is meant to be used for classifying either data nodes or instances of data nodes from different YANG modules and identifying their characteristic data. Tags may be registered as well as assigned during the definition of the module, assigned by implementations, or dynamically defined and set by users. This document also provides guidance to future YANG data model writers; as such, this document updates RFC 8407.