“Every page made by our software was generated by a program written in Rtml. We called these programs templates to make them less frightening, but they were real programs. In fact, they were Lisp programs. Users could write their own Rtml templates to describe what they wanted their pages to look like. We had a structure editor for manipulating these templates, a lot like the structure editor they had in Interlisp. Instead of typing free-form text, you cut and pasted bits of code together. This meant that it was impossible to get syntax errors. It also meant that we didn’t have to display the parentheses in the underlying s-expressions: we could show structure by indentation. By this means we made the language look a lot less threatening.