diff --git a/xen/include/public/event_channel.h b/xen/include/public/event_channel.h
index 0d91a1c4afab..c5548d206c74 100644
--- a/xen/include/public/event_channel.h
+++ b/xen/include/public/event_channel.h
@@ -114,10 +114,10 @@ typedef struct evtchn_bind_interdomain evtchn_bind_interdomain_t;
  * EVTCHNOP_bind_virq: Bind a local event channel to VIRQ <irq> on specified
  * vcpu.
  * NOTES:
- *  1. Virtual IRQs are classified as per-vcpu or global. See the VIRQ list
- *     in xen.h for the classification of each VIRQ.
- *  2. Global VIRQs must be allocated on VCPU0 but can subsequently be
- *     re-bound via EVTCHNOP_bind_vcpu.
+ *  1. Virtual IRQs are classified as per-vcpu, per-domain or global. See the
+ *     VIRQ list in xen.h for the classification of each VIRQ.
+ *  2. Per-domain and global VIRQs must be allocated on vCPU0 but can
+ *     subsequently be re-bound via EVTCHNOP_bind_vcpu.
  *  3. Per-vcpu VIRQs may be bound to at most one event channel per vcpu.
  *     The allocated event channel is bound to the specified vcpu and the
  *     binding cannot be changed.
diff --git a/xen/include/public/xen.h b/xen/include/public/xen.h
index e051f989a5ca..75b1c1d597f9 100644
--- a/xen/include/public/xen.h
+++ b/xen/include/public/xen.h
@@ -159,25 +159,34 @@ DEFINE_XEN_GUEST_HANDLE(xen_ulong_t);
  *
  * Virtual interrupts that a guest OS may receive from Xen.
  *
- * In the side comments, 'V.' denotes a per-VCPU VIRQ while 'G.' denotes a
- * global VIRQ. The former can be bound once per VCPU and cannot be re-bound.
- * The latter can be allocated only once per guest: they must initially be
- * allocated to VCPU0 but can subsequently be re-bound.
+ * There are three types:
+ *
+ * 1. (V) Per-vcpu:
+ *    These can be bound once per vCPU, each using a different evtchn port.
+ *    An evtchn for one vCPU cannot be rebound to a different vCPU.
+ *
+ * 2. (D) Per-domain:
+ *    These can be bound once per domain.  They must be bound on vCPU 0 first,
+ *    but can be rebound to other vCPUs afterwards.
+ *
+ * 3. (G) Global:
+ *    Like per-domain, but can only be bound to a single domain at a time.
+ *    The owning domain must unbind before a new domain can bind.
  */
 /* ` enum virq { */
 #define VIRQ_TIMER      0  /* V. Timebase update, and/or requested timeout.  */
 #define VIRQ_DEBUG      1  /* V. Request guest to dump debug info.           */
-#define VIRQ_CONSOLE    2  /* G. (DOM0) Bytes received on emergency console. */
-#define VIRQ_DOM_EXC    3  /* G. (DOM0) Exceptional event for some domain.   */
-#define VIRQ_TBUF       4  /* G. (DOM0) Trace buffer has records available.  */
-#define VIRQ_DEBUGGER   6  /* G. (DOM0) A domain has paused for debugging.   */
+#define VIRQ_CONSOLE    2  /* G. Bytes received on emergency console.        */
+#define VIRQ_DOM_EXC    3  /* G. Exceptional event for some domain.          */
+#define VIRQ_TBUF       4  /* G. Trace buffer has records available.         */
+#define VIRQ_DEBUGGER   6  /* G. A domain has paused for debugging.          */
 #define VIRQ_XENOPROF   7  /* V. XenOprofile interrupt: new sample available */
-#define VIRQ_CON_RING   8  /* G. (DOM0) Bytes received on console            */
-#define VIRQ_PCPU_STATE 9  /* G. (DOM0) PCPU state changed                   */
-#define VIRQ_MEM_EVENT  10 /* G. (DOM0) A memory event has occurred          */
-#define VIRQ_ARGO       11 /* G. Argo interdomain message notification       */
-#define VIRQ_ENOMEM     12 /* G. (DOM0) Low on heap memory       */
-#define VIRQ_XENPMU     13 /* V.  PMC interrupt                              */
+#define VIRQ_CON_RING   8  /* G. Bytes received on console                   */
+#define VIRQ_PCPU_STATE 9  /* G. PCPU state changed                          */
+#define VIRQ_MEM_EVENT  10 /* G. A memory event has occurred                 */
+#define VIRQ_ARGO       11 /* D. Argo interdomain message notification       */
+#define VIRQ_ENOMEM     12 /* G. Low on heap memory                          */
+#define VIRQ_XENPMU     13 /* V. PMC interrupt                               */
 
 /* Architecture-specific VIRQ definitions. */
 #define VIRQ_ARCH_0    16
