Fun! It's been a while.
Is my following interpretation of the rules for "Non Re-Encoding/Decoding" correct?..
- while $asc($) is disallowed (a literal "$"), $asc($true) is allowed (as $true is built-in)
- given a built-in string function $builtin1(): while $builtin1($builtin2 $+ $builtin3) is allowed, $builtin1($builtin2 $builtin3) is not, because it would be using a literal space as part of the input