Construct a subsection with a title and some content.
This should be used inside a section.
Currently this produces a level-4 heading, which is adequate since section produces a level-3 heading. As mentioned in section, the exact heading level could be made customizable; in order to enforce the right relationship between the levels of section and subsection, this could be based on a changeable global setting (e.g. in a table).
Macro:
(defmacro subsection (title &rest content) (cons '&& (cons (cons 'h4 (cons title 'nil)) content)))