Syntax vs Semantics is distinguished by ParseError vs ValidationError in the eno libraries - I'll keep the importance of distinguishing them in mind for the schema development too - thanks for pointing this out!

Right now only an ASCII colon is interpreted as an operator, but this looks like a question to thoroughly consider for the next and final spec (which is planned for 2019, currently we're in frozen RC) - work on this currently happens at https://github.com/eno-lang/eno.

There is escaping for arbitrary keys by using backticks - see the advanced language feature documentation at https://eno-lang.org/advanced/, in the case of # #twitter you wouldn't need it though unless you omit the space.

Thanks for your input, appreciate it!