+
+ikiwiki also has an older syntax for preprocessor directives, which requires a
+space in directives to distinguish them from [[wikilinks|wikilink]]. This
+syntax has several disadvantages: it requires a space after directives with no
+parameters (such as `\[[pagecount ]]`), and it prohibits spaces in
+[[wikilinks|wikilink]]. ikiwiki now provides the `!`-prefixed syntax shown
+above as the preferred alternative. However, ikiwiki still supports wikis
+using the older syntax, if the `prefix_directives` option is not enabled.
+For backward compatibility with existing wikis, this option currently
+defaults to off, so ikiwiki supports the old syntax.