Using capitalized keywords in order to make it easy to add keywords in the future reveals the author is probably not very familiar with the science of parsing.

Using capitalized keywords in order to make it easy to add keywords in the future reveals the author is probably not very familiar with the science of parsing. It's quite possible to introduce new keywords in future versions of the language and make sure your compiler won't choke simply because the word is being used as a variable name instead of an identifier.