diff --git a/draft-ymbk-sidrops-8210bis.xml b/draft-ymbk-sidrops-8210bis.xml
index d65b2bc..f7b94a9 100644
--- a/draft-ymbk-sidrops-8210bis.xml
+++ b/draft-ymbk-sidrops-8210bis.xml
@@ -945,7 +945,7 @@
 0          8          16         24        31
 .-------------------------------------------.
 | Protocol |   PDU    |                     |
-| Version  |   Type   |         zero        |
+| Version  |   Type   |        zero         |
 |    2     |    11    |                     |
 +-------------------------------------------+
 |                                           |
@@ -967,29 +967,41 @@
           </artwork>
         </figure>
 	<t>The ASPA PDU is to support <xref
-	target="I-D.ietf-sidrops-aspa-profile"/>.  Receipt of an ASPA
-	PDU announcement when the router already has an ASPA PDU with
-	the same Customer Autonomous System Number, replaces the
-	previous one.  This is to avoid a race condition when a BGP
-	announcement is received between an withdrawn PDU and a new
-	announced PDU.  Therfore, the cache SHOULD deliver entire data
-	of an ASPA record in a single ASPA PDU.
+	target="I-D.ietf-sidrops-aspa-profile"/>.  An ASPA PDU
+	represents one single customer AS and zero or more provider ASs
+	for a particular Address Family.  Receipt of an ASPA PDU
+	announcement when the router already has an ASPA PDU with the
+	same Customer Autonomous System Number and the same Address
+	Family (see Flags field), replaces the previous one.  This is to
+	avoid a race condition when a BGP announcement is received
+	between an withdrawn PDU and a new announced PDU.  Therfore, the
+	cache SHOULD deliver entire data of an ASPA record in a single
+	ASPA PDU.
 	</t>
         <t>
-          The lowest-order bit of the Flags field is 1 for an
-          announcement and 0 for a withdrawal.  Withdrawal of a
-	  non-existant or non-matching ASPA PDU is an error.
-        </t>
-        <t>
-          The Provider AS Count is the number of 32-bit Provider
-          Autonomous System Numbers in the PDU.  There may be none.
-        </t>
-        <t>
+          The Flags field is defined as follows:</t>
+    <figure>
+      <artwork>
+    Bit     Bit Name
+    ----    -------------------
+     0      Announce/Withdraw (ann == 0, with == 1)
+     1      AFI (IPv4 == 0, IPv6 == 1)
+     3-7    Reserved, must be zero
+       </artwork>
+    </figure>
+        <t>The Provider AS Count is the number of Provider Autonomous
+        System Number(s) at the end of the PDU, and may be zero or more.
+	</t>
+	<t>
           The Customer Autonomous System Number is the 32-bit
           Autonomous System Number of the customer which signed the
           PDU.  There may be only one ASPA for a Customer Autonomous
 	  System Number active at any time.
         </t>
+        <t>
+          The Provider AS Count is the number of 32-bit Provider
+          Autonomous System Numbers in the PDU.  There may be none.
+        </t>
         <t>
           There are zero or more 32-bit Provider Autonomous System
           Number fields; see <xref