diff --git a/doc/plugins/po.mdwn b/doc/plugins/po.mdwn
index 6c0d49197..6a2409847 100644
--- a/doc/plugins/po.mdwn
+++ b/doc/plugins/po.mdwn
@@ -309,6 +309,12 @@ does. This is actually a duplicate for
 [[bugs/pagetitle_function_does_not_respect_meta_titles]], which might
 be fixed by something like [[todo/using_meta_titles_for_parentlinks]].
 
+### source files format
+
+Markdown is supported, great, but what about others? The set of file
+formats supported both in ikiwiki and po4a probably is greater than
+`{markdown}`.
+
 Translation quality assurance
 -----------------------------