Hickory Hill Consulting The BGP (RFC4271) Tunnel Encapsulation Attribute (TEA) is defined in RFC9012. Currently proposed BGP specifications in the IDR and BESS Working groups have defined new tunnels and new parameters for these tunnels in Sub-TLV. The Segment Routing usage of the TEA has suggested a number of new Sub-TLVs. This document provides guidelines to help authors quickly write correct text for new tunnels (defined in tunnel TLVs) and new Sub-TLVs. These guidelines are given as "templates" to aid new authors. More experience authors should view these templates as a list of expected content. One additional challenge for tunnels using the PMSI tunnels is to carefully define the interaction between PMSI tunnels and TEA tunnels.