+;; We use the following pair of hashmaps to form the cache: one
+;; for the content (rendered server responses), and one for the
+;; position of point within the content.
+;;
+;; The keys for both of these hashmaps are the page addresses, and
+;; the cache persists for as long as the emacs session.
+;;
+;; Whether or not to use cached content is a decision made by the
+;; specific renderer. Some renderers, such as elpher-render-download,
+;; never cache.
+