Author: Your name. Optional: company and optional contact email.
Short description goes here.
Longer description goes here include syntax and technical detail. Also include details of influences (if any) and relevant comparisons, e.g. Haskell does X whilst Scala does Y.
Details of why this is desired and the advantages that it brings. You should also mention any disadvanges it might bring, like code complexity or confusion with any other existing syntax.
Examples of valid and invalid use of your syntax extension.
Optional. You could describe your extension in terms of EBNF, and bonus points if you describe how it fits into the existing EBNF of XPath ;-)