Comment by hgs3

Yes, the "${}" would be for the program to evaluate; referencing environment variables that way isn't uncommon in Unix configuration files.

"Reverse Solidus" is the Unicode name for the character [1], so if you don't like the name, blame Unicode :)

I hadn't thought of using '[' and ']' for multi-line directives, that's an interesting suggestion. It vaguely resembles arrays as they appear in various other languages. It fits with Confetti's design of, ultimately, being user interpreted.

[1] https://www.compart.com/en/unicode/U+005C