Instead of enumerating Extension keywords, the spec currently refers readers to the Profile keywords since they are nearly identical: Defining extensions is similar to defining profiles , except that the parent of an extension is not required. We agree, however, that it would be better to list the keywords here as in other sections. This is not only more consistent, but prevents the reader from having to jump to another section of the specification. Many keywords do not require additional explanation, as their use is fairly obvious. Other keywords, however, do require additional explanation in the text. These keywords may support multiple options, have complicated requirements, or exhibit non-obvious behaviors. As such, we believe it is important for us to specifically call them out and provide the detail necessary for proper use and implementation. Extension Context is one of these keywords, hence the more thorough description.