diff --git a/conts/libl4/include/l4lib/arch-arm/syslib.h b/conts/libl4/include/l4lib/arch-arm/syslib.h
index b8b2245..e062a47 100644
--- a/conts/libl4/include/l4lib/arch-arm/syslib.h
+++ b/conts/libl4/include/l4lib/arch-arm/syslib.h
@@ -128,9 +128,14 @@ static inline int l4_get_retval(void)
 }
 
 /*
- * If we're about to do another ipc, this saves the last ipc's
- * parameters such as the sender and tag information.
- * Any previously saved data in save slots are destroyed.
+ * This is useful for stacked IPC. A stacked IPC happens
+ * when a new IPC is initiated before concluding the current
+ * one.
+ *
+ * This saves the last ipc's parameters such as the sender
+ * and tag information. Any previously saved data in save
+ * slots are destroyed. This is fine as IPC stacking is only
+ * useful if done once.
  */
 static inline void l4_save_ipcregs(void)
 {
diff --git a/include/l4/api/ipc.h b/include/l4/api/ipc.h
index 4b291e1..0f66684 100644
--- a/include/l4/api/ipc.h
+++ b/include/l4/api/ipc.h
@@ -9,15 +9,18 @@
 /* Pagefault */
 #define L4_IPC_TAG_PFAULT		0
 
+#define L4_IPC_FLAGS_TYPE_MASK		0x0000000F
 #define L4_IPC_FLAGS_SHORT		0x00000000	/* Short IPC involves just primary message registers */
 #define L4_IPC_FLAGS_FULL		0x00000001	/* Full IPC involves full UTCB copy */
 #define L4_IPC_FLAGS_EXTENDED		0x00000002	/* Extended IPC can page-fault and copy up to 2KB */
+
+/* Extended IPC extra fields */
 #define L4_IPC_FLAGS_MSG_INDEX_MASK	0x00000FF0	/* Index of message register with buffer pointer */
-#define L4_IPC_FLAGS_TYPE_MASK		0x0000000F
 #define L4_IPC_FLAGS_SIZE_MASK		0x0FFF0000
 #define L4_IPC_FLAGS_SIZE_SHIFT		16
 #define L4_IPC_FLAGS_MSG_INDEX_SHIFT	4
 
+
 #define L4_IPC_EXTENDED_MAX_SIZE	(SZ_1K*2)
 
 #if defined (__KERNEL__)
diff --git a/include/l4/glue/arm/message.h b/include/l4/glue/arm/message.h
index 0d9a8c8..ab859bb 100644
--- a/include/l4/glue/arm/message.h
+++ b/include/l4/glue/arm/message.h
@@ -14,7 +14,7 @@
  * the microkernel will read and they have system-wide meaning.
  *
  * Primary message registers:
- * r3 - r8: These 6 registers are the primary message registers MR0-MR6
+ * r3 - r8: These 6 registers are the primary message registers MR0-MR6.
  * Their format is application-specific, i.e. the microkernel imposes no
  * format restrictions on them.
  *