diff --git a/geomagio/TimeseriesFactory.py b/geomagio/TimeseriesFactory.py
index f631b90aaadff0b8cef50f2ae6388d5233124420..b97e99dc8ae122c25d18ce3cd0f592f6196bf62f 100644
--- a/geomagio/TimeseriesFactory.py
+++ b/geomagio/TimeseriesFactory.py
@@ -9,6 +9,14 @@ import Util
 class TimeseriesFactory(object):
     """Base class for timeseries factories.
 
+    Add input support by:
+        - implementing `parse_string`
+        - or, overriding `get_timeseries`
+
+    Add output support by:
+        - implementing `write_file`
+        - or, overriding `put_timeseries`
+
     Attributes
     ----------
     observatory : str