+#### `rcs_receive()`
+
+This is called when ikiwiki is running as a pre-receive hook (or
+equivalent), and is testing if changes pushed into the RCS from an
+untrusted user should be accepted. This is optional, and doesn't make
+sense to implement for all RCSs.
+
+It should examine the incoming changes, and do any sanity
+checks that are appropriate for the RCS to limit changes to safe file adds,
+removes, and changes. If something bad is found, it should exit
+nonzero, to abort the push. Otherwise, it should return a list of
+files that were changed, in the form:
+
+ {
+ file => # name of file that was changed
+ action => # either "add", "change", or "remove"
+ path => # temp file containing the new file content, only
+ # needed for "add"/"change", and only if the file
+ # is an attachment, not a page
+ }
+
+The list will then be checked to make sure that each change is one that
+is allowed to be made via the web interface.
+