Something similar to sxml? https://en.wikipedia.org/wiki/SXML https://en.wikipedia.org/wiki/SXML XML has attributes which S-exprs don't. This can be solved by

Something similar to sxml? https://en.wikipedia.org/wiki/SXML https://en.wikipedia.org/wiki/SXML XML has attributes which S-exprs don't. This can be solved by convention (as SXML does) and doesn't really represent a difference in expressibility. S-exprs have quote and unquote which XML doesn't. This is a fundamental difference and makes it hard to convert Lisp code that mixes code and data representations.