and undef if a rebuild could be needed in some circumstances, but is not
strictly required.
+### targetpage
+
+ hook(type => "targetpage", id => "foo", call => \&targetpage);
+
+This hook can be used to override the name of the file a page should
+be compiled into.
+
+It should return the target filename.
+
## Plugin interface
To import the ikiwiki plugin interface: