As for the '<' and '>' to open and close an element, there are two potential kinds of syntax design. Option 1 is to use some explicit delimiters. Mark 1.0 has settled on '<' and '>'. Mark 0.11 was using '{' and '}', which I felt confusing with map. So I changed to '<' and '>', to make it consistent with HTML/JSX and XML, which most developers are already used to. Option 2 is to use indentation to delimit the enclosed child content, like in Python and YAML.

Option 2 looks cleaner for configuration kind of usage. However, Mark is designed to be embedded in a scripting language, and used beyond just configuration files. Unless the scripting language uses indentation as delimiter, like Python, option 2 will not work.

Personally, I prefer C/Java/JS family of languages that has insignificant whitespace. So Mark is designed to use explicit delimiters '<' and '>' to enclose an element.

Hope that explains one of the most important syntax designs of Mark.