diff --git a/specification/archSpec/base/cascading-of-attributes-from-map-to-map.dita b/specification/archSpec/base/cascading-of-attributes-from-map-to-map.dita
index f8b0e628..1019690e 100644
--- a/specification/archSpec/base/cascading-of-attributes-from-map-to-map.dita
+++ b/specification/archSpec/base/cascading-of-attributes-from-map-to-map.dita
@@ -23,6 +23,7 @@
       <li><xmlatt>translate</xmlatt></li>
       <li><xmlatt>processing-role</xmlatt></li>
       <li><xmlatt>cascade</xmlatt></li>
+      <li rev="2.0"><xmlatt>subjectrefs</xmlatt></li>
     </ul>
     <p>As with values that cascade within a map, the cascading is additive
       if the attribute permits multiple values<ph rev="review-k">,
diff --git a/specification/archSpec/base/cascading-of-roles-in-specialized-maps.dita b/specification/archSpec/base/cascading-of-roles-in-specialized-maps.dita
index 1cb88cef..3a3a0b2c 100644
--- a/specification/archSpec/base/cascading-of-roles-in-specialized-maps.dita
+++ b/specification/archSpec/base/cascading-of-roles-in-specialized-maps.dita
@@ -16,9 +16,9 @@
  </prolog>
  <conbody>
     <!--IGNORE may-must-should word-->
-    <draft-comment author="Kristen J Eberlein" audience="spec-editors" time="04 July 2019">
-      <p>We need to look at the instances of "should" in this topic. Can they be recast? Do we need
-        to introduce RFC-2119 language?</p>
+    <draft-comment author="Kristen J Eberlein" time="04 June 2022">
+      <p>Proposal #670, championed by Robert Anderson, will rework this
+        content.</p>
     </draft-comment>
     <p>The semantic role reflects the <xmlatt>class</xmlatt> hierarchy of
       the referencing <xmlelement>topicref</xmlelement> element<ph
@@ -36,12 +36,7 @@
    role of "topic"), or when a <xmlelement>mapref</xmlelement> element references a DITA map (giving
    it the role of "DITA map").</p>
     <!--IGNORE may-must-should word-->
-    <draft-comment author="rodaande" time="8 Feb 2022">The following paragraph includes the
-      statement: "the non-default behavior should be clearly specified"<p>We do not say how or
-        where. For mapgroup, I believe it is only specified here in this topic. I think either we
-        need this as part of every mapgroup element definition, in "Processing expectations", or we
-        need a clear table here listing every element where this behavior does not
-      apply.</p></draft-comment>
+    <!--<draft-comment author="rodaande" time="8 Feb 2022">The following paragraph includes the statement: "the non-default behavior should be clearly specified"<p>We do not say how or where. For mapgroup, I believe it is only specified here in this topic. I think either we need this as part of every mapgroup element definition, in "Processing expectations", or we need a clear table here listing every element where this behavior does not apply.</p></draft-comment>-->
   <p>Unless otherwise instructed, a specialized <xmlelement>topicref</xmlelement> element that
       references a map supplies a role for the referenced content. This means that, in effect, the
         <xmlatt>class</xmlatt> attribute of the referencing element cascades to top-level topicref
diff --git a/specification/archSpec/base/example-a-subject-scheme-map-used-to-define-taxonomic-subjects.dita b/specification/archSpec/base/example-a-subject-scheme-map-used-to-define-taxonomic-subjects.dita
new file mode 100644
index 00000000..2eee5866
--- /dev/null
+++ b/specification/archSpec/base/example-a-subject-scheme-map-used-to-define-taxonomic-subjects.dita
@@ -0,0 +1,71 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE concept PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd">
+<concept
+  id="example-a-subject-scheme-map-used-to-define-taxonomic-subjects"
+  rev="2.0">
+  <title>Example: A subject scheme map used to define taxonomic
+    subjects</title>
+  <shortdesc>A subject scheme map can be used to define taxonomic subjects.
+    Once defined, the subjects can be referenced by applying a
+      <xmlatt>subjectrefs</xmlatt> attribute to a
+      <xmlelement>topicref</xmlelement> element.</shortdesc>
+  <prolog>
+    <metadata>
+      <keywords>
+        <indexterm>examples<indexterm>subject scheme
+              maps<indexterm>defining taxonomic
+            subjects</indexterm></indexterm></indexterm>
+      </keywords>
+    </metadata>
+  </prolog>
+  <conbody>
+    <p>The following subject scheme map defines a set of subjects that are
+      used to classify content:</p>
+    <codeblock>&lt;subjectScheme>
+  &lt;subjectdef keys="content-types">
+    &lt;subjectdef keys="conceptual-material"/>
+    &lt;subjectdef keys="reference"/>
+    &lt;subjectdef keys="tutorial"/>
+  &lt;/subjectdef>
+  &lt;subjectdef keys="operating-systems">
+    &lt;subjectdef keys="linux"/>
+    &lt;subjectdef keys="macosx"/>
+    &lt;subjectdef keys="windows"/>
+  &lt;/subjectdef>
+  &lt;subjectdef keys="user-tasks">
+    &lt;subjectdef keys="administering"/>
+    &lt;subjectdef keys="developing"/>
+    &lt;subjectdef keys="installing"/>
+    &lt;subjectdef keys="troubleshooting"/>
+  &lt;/subjectdef>
+&lt;/subjectScheme></codeblock>
+    <p>The keys assigned to the subject definitions can be referenced by
+      specifying the <xmlatt>subjectrefs</xmlatt> attribute on topic
+      references in a navigation map:</p>
+    <codeblock>&lt;map>
+&lt;title>User assistance for the Acme Widget&lt;/title>
+&lt;!-- ... -->
+&lt;topicref keyref="install-overview" <b>subjectrefs="installing"</b>>
+  &lt;topicref keyref="install-linux"/>
+  &lt;topicref keyref="install-macosx"/>
+  &lt;topicref keyref="install-windows"/>
+  &lt;topicref keyref="install-troubleshooting" <b>subjectrefs="troubleshooting"</b>/>
+&lt;/topicref>
+&lt;!-- ... -->
+&lt;/map></codeblock>
+    <p>Because the <xmlatt>subjectrefs</xmlatt> attribute cascades, the
+      effective value of the above markup is the same as the following
+      markup:</p>
+    <codeblock>&lt;map>
+&lt;title>User assistance for the Acme Widget&lt;/title>
+&lt;!-- ... -->
+&lt;topicref keyref="install-overview" subjectrefs="installing">
+  &lt;topicref keyref="install-linux" subjectrefs="installing"/>
+  &lt;topicref keyref="install-macosx" subjectrefs="installing"/>
+  &lt;topicref keyref="install-windows" subjectrefs="installing"/>
+  &lt;topicref keyref="install-troubleshooting" subjectrefs="installing troubleshooting"/>
+&lt;/topicref>
+&lt;!-- ... -->
+&lt;/map></codeblock>
+  </conbody>
+</concept>
diff --git a/specification/archSpec/base/example-cascade-map-to-map-attributes.dita b/specification/archSpec/base/example-cascade-map-to-map-attributes.dita
index 79713a4a..bf29a9d9 100644
--- a/specification/archSpec/base/example-cascade-map-to-map-attributes.dita
+++ b/specification/archSpec/base/example-cascade-map-to-map-attributes.dita
@@ -15,12 +15,13 @@
   </prolog>
   <conbody>
     <p>Assume the following references in
-      <filepath>test.ditamap</filepath>:<codeblock id="codeblock_sx1_fp5_nsb">&lt;map>
+      <filepath>test.ditamap</filepath>:<codeblock>&lt;map>
   &lt;topicref href="a.ditamap" format="ditamap" toc="no"/>
-  &lt;mapref   href="b.ditamap" audience="developer"/>
-  &lt;mapref   href="c.ditamap#branch2" platform="myPlatform"/>
+  &lt;mapref href="b.ditamap" audience="developer"/>
+  &lt;mapref href="c.ditamap#branch2" platform="myPlatform"/>
+  <ph rev="2.0">&lt;mapref> href="d.ditamap" subjectrefs="puzzles"/></ph>
 &lt;/map></codeblock></p>
-    <ul id="ul_vx1_fp5_nsb">
+    <ul>
       <li>The map <filepath>a.ditamap</filepath> is treated as if
           <codeph>toc="no"</codeph> is specified on the root
           <xmlelement>map</xmlelement> element. This means that the topics
@@ -29,15 +30,27 @@
         except for branches within the map that explicitly set
           <codeph>toc="yes"</codeph>.</li>
       <li>The map <filepath>b.ditamap</filepath> is treated as if
-          <codeph>audience="developer"</codeph> is set on the root <xmlelement>map</xmlelement>
-        element. If the <xmlatt>audience</xmlatt> attribute is already set on the root
-          <xmlelement>map</xmlelement> element within <filepath>b.ditamap</filepath>, the value
-        "developer" is added to any existing values.</li>
+          <codeph>audience="developer"</codeph> is set on the root
+          <xmlelement>map</xmlelement> element. If the
+          <xmlatt>audience</xmlatt> attribute is already set on the root
+          <xmlelement>map</xmlelement> element within
+          <filepath>b.ditamap</filepath>, the value
+          <keyword>developer</keyword> is added to any existing
+        values.</li>
       <li>The element with <codeph>id="branch2"</codeph> within the map
-          <filepath>c.ditamap</filepath> is treated as if <codeph>platform="myPlatform"</codeph> is
-        specified on that element. If the <xmlatt>platform</xmlatt> attribute is already specified
-        on the element with <codeph>id="branch"</codeph>, the value<keyword>myPlatform</keyword> is
-        added to existing values.</li>
+          <filepath>c.ditamap</filepath> is treated as if
+          <codeph>platform="myPlatform"</codeph> is specified on that
+        element. If the <xmlatt>platform</xmlatt> attribute is already
+        specified on the element with <codeph>id="branch"</codeph>, the
+          value<keyword>myPlatform</keyword> is added to existing
+        values.</li>
+      <li rev="2.0">The map <filepath>d.ditamap</filepath> is treated as if
+          <codeph>subjectrefs="puzzles"</codeph> is set on the root
+          <xmlelement>map</xmlelement> element. If the
+          <xmlatt>subjectrefs</xmlatt> attribute is already set on the root
+          <xmlelement>map</xmlelement> element within
+          <filepath>d.ditamap</filepath>, the value
+          <keyword>puzzles</keyword> is added to any existing values.</li>
     </ul>
   </conbody>
 </concept>
diff --git a/specification/archSpec/base/example-cascading-topicref-roles.dita b/specification/archSpec/base/example-cascading-topicref-roles.dita
index c30cec3b..4601a751 100644
--- a/specification/archSpec/base/example-cascading-topicref-roles.dita
+++ b/specification/archSpec/base/example-cascading-topicref-roles.dita
@@ -17,6 +17,10 @@
     </metadata>
   </prolog>
   <conbody>
+    <draft-comment author="Kristen J Eberlein" time="04 June 2022">
+      <p>Proposal #670, championed by Robert Anderson, will rework this
+        content.</p>
+    </draft-comment>
     <p>Consider the scenario of a <xmlelement>chapter</xmlelement> element from the Book map
       specialization that references a DITA map. This scenario could take several forms:<dl
         id="dl_ohc_nq5_nsb">
diff --git a/specification/archSpec/base/processing-cascading-attributes-in-a-map.dita b/specification/archSpec/base/processing-cascading-attributes-in-a-map.dita
index 857abbf6..e7eab271 100644
--- a/specification/archSpec/base/processing-cascading-attributes-in-a-map.dita
+++ b/specification/archSpec/base/processing-cascading-attributes-in-a-map.dita
@@ -5,6 +5,10 @@
     <shortdesc>Certain rules apply to processors when they process cascading attributes in a
         map.</shortdesc>
     <conbody>
+    <draft-comment author="Kristen J Eberlein" time="04 June 2022">
+      <p>Robert Anderson has an open action item to rework the ordered
+        list.</p>
+    </draft-comment>
         <p>When determining the value of an attribute, processors <term
         outputclass="RFC-2119">MUST</term> evaluate each attribute on each
       individual element in a specific order<ph rev="review-k">. This</ph>
diff --git a/specification/archSpec/base/subject-scheme-maps.ditamap b/specification/archSpec/base/subject-scheme-maps.ditamap
index 6eb2f93a..cada8e7d 100644
--- a/specification/archSpec/base/subject-scheme-maps.ditamap
+++ b/specification/archSpec/base/subject-scheme-maps.ditamap
@@ -9,8 +9,11 @@
   <topicref href="processing-controlled-attribute-values.dita"/>
     <!--<topicref href="extending-a-subject-scheme.dita"/>-->
     <!--<topicref href="scaling-controlled-values-to-define-a-taxonomy.dita"/>-->
-    <topicref href="classification-maps.dita"/>
+    <!--<topicref href="classification-maps.dita"/>-->
+    <topicref href="the-subjectrefs-attribute.dita"/>
   <topicref href="examples-subjectScheme-maps.dita">
+      <topicref
+        href="example-a-subject-scheme-map-used-to-define-taxonomic-subjects.dita"/>
    <topicref href="example-subjectScheme-filtering.dita"/>
       <!--<topicref href="example-subjectScheme-extension.dita"/>-->
       <!--<topicref href="example-subjectScheme-extension-upwards.dita"/>-->
diff --git a/specification/archSpec/base/subjectSchema.dita b/specification/archSpec/base/subjectSchema.dita
index 109078de..fbf34661 100644
--- a/specification/archSpec/base/subjectSchema.dita
+++ b/specification/archSpec/base/subjectSchema.dita
@@ -34,12 +34,10 @@
         value that is not one of the controlled values. </ph>Controlled
       values can also be used to <ph rev="review-d">select </ph>content for
       filtering and flagging at build time.</p>
-        <p ><term>Subject definitions</term> are classifications and
-            sub-classifications that compose a tree. Subject definitions provide  semantics that can
-            be used in conjunction with taxonomies and ontologies. In conjunction with the
-            classification domain, subject definitions can be used for retrieval and traversal of
-            the content at run time when used with information viewing applications that provide
-            such functionality.</p>
+        <p><term>Subject definitions</term> are classifications and
+      sub-classifications that compose a tree. Subject definitions provide
+      semantics that can be used in conjunction with taxonomies and
+      ontologies.</p>
         <p >Key references to controlled values are resolved to a key
             definition using the same precedence rules as apply to any other key. However, once a
             key is resolved to a controlled value, that key reference does not typically result in
diff --git a/specification/archSpec/base/the-subjectrefs-attribute.dita b/specification/archSpec/base/the-subjectrefs-attribute.dita
new file mode 100644
index 00000000..0ec500f4
--- /dev/null
+++ b/specification/archSpec/base/the-subjectrefs-attribute.dita
@@ -0,0 +1,22 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE concept PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd">
+<concept id="the-subjectrefs-attribute" rev="2.0">
+  <title>The <xmlatt>subjectrefs</xmlatt> attribute</title>
+  <shortdesc>The <xmlatt>subjectrefs</xmlatt> attribute specifies one or
+    more keys that are defined by a subject definition in a subject scheme
+    map. Multiple values are separated by white space.</shortdesc>
+  <prolog>
+    <metadata>
+      <keywords>
+        <indexterm><xmlatt>subjectrefs</xmlatt><indexterm>overview</indexterm></indexterm>
+      </keywords>
+    </metadata>
+  </prolog>
+  <conbody>
+    <p>The <xmlatt>subjectrefs</xmlatt> attribute cascades. It can be used
+      on a <xmlelement>topicref</xmlelement> element to associate the
+      referenced topic with a subject defined in a subject scheme map.</p>
+    <p>The <xmlatt>subjectrefs</xmlatt> attribute has no meaning if it is
+      specified on a key definition that does not reference a resource.</p>
+  </conbody>
+</concept>
diff --git a/specification/common/conref-file.dita b/specification/common/conref-file.dita
index dd50ee1d..416e6a96 100644
--- a/specification/common/conref-file.dita
+++ b/specification/common/conref-file.dita
@@ -126,6 +126,7 @@ to alert more birds to the presence of your bird feeder.&lt;/shortdesc&gt;
                                                 <xmlatt>translate</xmlatt></li>
                                 <li><xmlatt>processing-role</xmlatt></li>
                                 <li ><xmlatt>cascade</xmlatt></li>
+        <li rev="2.0"><xmlatt>subjectrefs</xmlatt></li>
                         </ul>
                         <dl>
                                 <dlentry  id="deliveryTarget">
diff --git a/specification/resources/DITA2.0-spec.ditaval b/specification/resources/DITA2.0-spec.ditaval
index db796972..0ba0fa79 100644
--- a/specification/resources/DITA2.0-spec.ditaval
+++ b/specification/resources/DITA2.0-spec.ditaval
@@ -121,5 +121,13 @@
         <endflag>
             <alt-text>◄</alt-text>
         </endflag>-->
+  </revprop>
+        <revprop action="flag" color="blue" val="2.0">
+    <!--        <startflag>
+            <alt-text>►</alt-text>
+        </startflag>
+        <endflag>
+            <alt-text>◄</alt-text>
+        </endflag>-->
   </revprop>
 </val>