diff --git a/config.default.h b/config.default.h
index 9d99794..527941c 100644
--- a/config.default.h
+++ b/config.default.h
@@ -48,6 +48,8 @@ static Key key[] = { \
 	{ MODKEY|ShiftMask,		XK_q,		quit,		{ 0 } }, \
 };
 
+/* Query class:instance for regex matching info with following command:
+ * ; xprop | grep WM_CLASS | sed 's/"//g;s/,//g' | awk '{ printf("%s:%s", $4, $3) }' */
 #define RULES \
 static Rule rule[] = { \
 	/* class:instance regex		tags regex	isfloat */ \