+ * Following options to distinguish:
+ * - versioned: Used for modules with a version, because changing version
+ * numbers causes cache misses. This normally has a long expiry time.
+ * - unversioned: Used for modules without a version to propagate changes
+ * quickly to clients. Also used for modules with errors to recover quickly.
+ * This normally has a short expiry time.
+ *
+ * Expiry time for the options to distinguish:
+ * - server: Squid/Varnish but also any other public proxy cache between the
+ * client and MediaWiki.
+ * - client: On the client side (e.g. in the browser cache).