* `filter` is a reference to a function, that is called and passed a page,
and returns true if the page should be filtered out of the list.
* `sort` specifies a sort order for the list. See
- [[ikiwiki/PageSpec/sorting]] for the avilable sort methods.
+ [[ikiwiki/PageSpec/sorting]] for the avilable sort methods. Note that
+ if a sort method is specified that depends on the
+ page content (such as 'meta(foo)'), the deptype needs to be set to
+ a content dependency.
* `reverse` if true, sorts in reverse.
* `num` if nonzero, specifies the maximum number of matching pages that
will be returned.
It's ok if this is not implemented, and throws an error.
+If the RCS cannot determine a ctime for the file, return 0.
+
+#### `rcs_getmtime($)`
+
+This is used to get the page modification time for a file from the RCS, by
+looking it up in the history.
+
+It's ok if this is not implemented, and throws an error.
+
+If the RCS cannot determine a mtime for the file, return 0.
+
#### `rcs_receive()`
This is called when ikiwiki is running as a pre-receive hook (or