diff --git a/mps/manual/source/pool/ams.rst b/mps/manual/source/pool/ams.rst
index 9fb1f9a9103..59d5ccfbd57 100644
--- a/mps/manual/source/pool/ams.rst
+++ b/mps/manual/source/pool/ams.rst
@@ -180,9 +180,11 @@ AMS interface
     class.
 
     When creating a debugging AMS pool, :c:func:`mps_pool_create_k`
-    takes three keyword arguments: :c:macro:`MPS_KEY_FORMAT` and
-    :c:macro:`MPS_KEY_CHAIN` are as described above, and
-    :c:macro:`MPS_KEY_POOL_DEBUG_OPTIONS` specifies the debugging
+    accepts the following keyword arguments:
+    :c:macro:`MPS_KEY_FORMAT`, :c:macro:`MPS_KEY_CHAIN`,
+    :c:macro:`MPS_KEY_GEN`, and
+    :c:macro:`MPS_KEY_AMS_SUPPORT_AMBIGUOUS` are as described above,
+    and :c:macro:`MPS_KEY_POOL_DEBUG_OPTIONS` specifies the debugging
     options. See :c:type:`mps_pool_debug_option_s`.
 
     .. deprecated:: starting with version 1.112.
diff --git a/mps/manual/source/topic/debugging.rst b/mps/manual/source/topic/debugging.rst
index 1f2cb498cf4..61025e31367 100644
--- a/mps/manual/source/topic/debugging.rst
+++ b/mps/manual/source/topic/debugging.rst
@@ -50,9 +50,9 @@ debugging:
   for the pattern at any time by calling
   :c:func:`mps_pool_check_free_space`.
 
-The :term:`client program` may specify templates for both of these
-features via the :c:type:`mps_pool_debug_option_s` structure. This
-allows it to specify patterns:
+The :term:`client program` may optionally specify templates for both
+of these features via the :c:type:`mps_pool_debug_option_s` structure.
+This allows it to specify patterns:
 
 * that mimic illegal data values;
 
@@ -81,15 +81,15 @@ For example::
 
 .. c:type:: mps_pool_debug_option_s
 
-    The type of the structure passed as the
+    The type of the structure passed as the value for the optional
     :c:macro:`MPS_KEY_POOL_DEBUG_OPTIONS` keyword argument to
     :c:func:`mps_pool_create_k` when creating a debugging :term:`pool
     class`. ::
 
         typedef struct mps_pool_debug_option_s {
-            void *fence_template;
+            const void *fence_template;
             size_t fence_size;
-            void *free_template;
+            const void *free_template;
             size_t free_size;
         } mps_pool_debug_option_s;
 
@@ -114,6 +114,13 @@ For example::
     pieces smaller than the given size, for example to pad out part of
     a block that was left unused because of alignment requirements.
 
+    If the client omits to pass the
+    :c:macro:`MPS_KEY_POOL_DEBUG_OPTIONS` keyword argument to
+    :c:func:`mps_pool_create_k`, then the fencepost template consists
+    of the four bytes ``50 4F 53 54`` (``POST`` in ASCII), and the
+    free space template consists of the four bytes ``46 52 45 45``
+    (``FREE`` in ASCII).
+
 
 .. c:function:: void mps_pool_check_fenceposts(mps_pool_t pool)