diff --git a/docs/building/filters/empty.rst b/docs/building/filters/empty.rst
new file mode 100644
index 00000000..15870a97
--- /dev/null
+++ b/docs/building/filters/empty.rst
@@ -0,0 +1,6 @@
+#######
+ empty
+#######
+
+The ``empty`` filter is for debugging purposes. It always returns an
+empty set of fields.
diff --git a/docs/building/filters/noop.rst b/docs/building/filters/noop.rst
new file mode 100644
index 00000000..ad5025b7
--- /dev/null
+++ b/docs/building/filters/noop.rst
@@ -0,0 +1,6 @@
+######
+ noop
+######
+
+The ``noop`` filter is for debugging purposes. It returns its input
+unchanged.
diff --git a/docs/building/filters/unrotate_winds.rst b/docs/building/filters/unrotate_winds.rst
new file mode 100644
index 00000000..8a8b53c5
--- /dev/null
+++ b/docs/building/filters/unrotate_winds.rst
@@ -0,0 +1,3 @@
+###############
+ unrotate_wind
+###############