diff --git a/msg/LQPtuCommandData.msg b/msg/LQPtuCommandData.msg
index 96db46251f768d573e2ca2ae1d0f16cbf2229bda..07360f7516344a6d08db959e7ec8945a911f51cf 100644
--- a/msg/LQPtuCommandData.msg
+++ b/msg/LQPtuCommandData.msg
@@ -1,5 +1,19 @@
 # pan, tilt, roll values in degrees
-float64 pan
-float64 tilt
-float64 roll
-int32 mode 
+#
+# mode=1, body relative
+#
+# mode=0:
+# pan behaves as in mode 1
+# tilt is relative forward direction in the horisontal plane
+# roll similar as for tilt
+#
+
+int32 MODE_PTU_STABILIZED=0
+int32 MODE_PTU_NON_STABILIZED=1
+
+int32 mode       # mode value deciding the meaning of pan, tilt, roll
+
+float64 pan      # -90 - 90, mode=1, positive clockwise
+float64 tilt     # -55 - 5, mode=1, positive up
+float64 roll     # -30 - 30, mode=1, vector out, positive clockwise
+