@@ -111,6 +111,11 @@ inline element must return an inline, and a block element must
111111remain a block element after filter application. Pandoc will
112112throw an error if this condition is violated.
113113
114+If there is no function matching the element's node type, then
115+the filtering system will look for a more general fallback
116+function. Two fallback functions are supported, `Inline` and
117+`Block`. Each matches elements of the respective type.
118+
114119Elements without matching functions are left untouched.
115120
116121See [module documentation](pandoc-module.html) for a list of pandoc