-#define DM_INC 0x00004000
-#define DM_DEC 0x00008000
-#define DM_FIX 0x0000c000
-#define SM_INC 0x00001000
-#define SM_DEC 0x00002000
-#define SM_FIX 0x00003000
+#define DM_INC 0x00004000 /* Destination addresses are incremented */
+#define DM_DEC 0x00008000 /* Destination addresses are decremented */
+#define DM_FIX 0x0000c000 /* Destination address is fixed */
+#define SM_INC 0x00001000 /* Source addresses are incremented */
+#define SM_DEC 0x00002000 /* Source addresses are decremented */
+#define SM_FIX 0x00003000 /* Source address is fixed */