diff --git a/pic/MDR/MDR.c b/pic/MDR/MDR.c
index 2679576..3f3898b 100644
--- a/pic/MDR/MDR.c
+++ b/pic/MDR/MDR.c
@@ -1,4 +1,4 @@
-/* micro-controller firmware fot the Linear MDR receiver
+/* micro-controller firmware fot the Linear MDR/MDR2/MDR-U receiver
    Copyright (C) 2014 Kévin Redon <kingkevin@cuvoodoo.info>
 
    This program is free software; you can redistribute it and/or modify
@@ -23,14 +23,14 @@
 
 /* the peripherals connected to the pins */
 #define RELAY1 _RA2 /* pin 1 */
-#define RELAY2 _RA3 /* pin 2 */
+#define RELAY2 _RA3 /* pin 2 only for MDR2 */
 /* pin 3 is connected to ground */
 /* pin 4 is used as master clear */
 /* pin 5 is Vss (ground) */
 #define SWITCH1 _RB0 /* pin 6 (on ground when pressed) */
 #define LED _RB1 /* pin 7 (used as sink) */
 #define SWITCH2 _RB2 /* pin 8 (on ground when pressed) */
-/* pin 9 is for a secret function, set by jumper WJ1, Vdd per default */
+/* pin 9 is to identify board. Vdd for MDR, ground for MDR-U */
 /* pin 10 is not connected */
 /* pin 11 in not connected */
 /* pin 12, external 24LC256 EEPROM */
@@ -39,7 +39,7 @@
 /* pin 15 is clonnected to external 4MHz ceramic resonator */
 /* pin 16 is clonnected to external 4MHz ceramic resonator */
 #define RADIO _RA0 /* radio signal receiver, filtered by LM358N */
-/* pin 18 is for a secret function, set by jumper WJ2, Vdd per default */
+/* pin 18 is to identify board. Vdd for MDR, ground for MDR-U */
 
 /* simple functions */
 #define led_off() LATB |= LED