diff --git a/test-suite/metaschema-xspec/markdown-types/markdown-mix.xspec b/test-suite/metaschema-xspec/markdown-types/markdown-mix.xspec
new file mode 100644
index 000000000..18f24637d
--- /dev/null
+++ b/test-suite/metaschema-xspec/markdown-types/markdown-mix.xspec
@@ -0,0 +1,87 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<x:description 
+    xmlns:x="http://www.jenitennison.com/xslt/xspec"
+    xmlns:xs="http://www.w3.org/2001/XMLSchema"
+    xmlns:m="http://csrc.nist.gov/ns/oscal/metaschema/1.0"
+    xmlns="http://csrc.nist.gov/ns/oscal/metaschema/1.0/supermodel"
+    stylesheet="../../../toolchains/xslt-M4/converter-gen/markdown-to-supermodel-xml-converter.xsl"
+    run-as="external">
+
+<x:scenario label="When converting markdown to markup">
+    
+    <x:scenario label="to show it works on a simple line of content">
+        <x:call template="parse-markdown">
+            <x:param name="markdown-str" select="'Here''s some *paragraph* content.'" />
+            <x:param name="each-word" select="true()" />
+        </x:call>
+        <x:expect label="expressed as markup" select=".">
+            <p>Here's some <em>paragraph</em> content.</p>
+        </x:expect>
+    </x:scenario>
+    
+    <x:scenario label="and also working on a couple of lines">
+        <x:variable name="in" as="xs:string" xml:space="preserve">
+Here's some *paragraph* content.
+
+And a **second** paragraph.
+
+</x:variable>
+        <x:call template="parse-markdown">
+            <x:param name="markdown-str" select="$in" />
+        </x:call>
+        <x:expect label="expressed as markup" select=".">
+            <p>Here's some <em>paragraph</em> content.</p>
+            <p>And a <strong>second</strong> paragraph.</p>
+        </x:expect>
+    </x:scenario>
+    
+    <x:scenario label="reproducing OSCAL Issue #1151">
+        <!-- note in this example extra initial indenting can perturb the inferencing -->
+        <!-- we should split this into two, one for nesting, the other for superfluous indent-->
+        <!-- but also test under Commonmark  etc.! https://babelmark.github.io/ note that superfluous indents are not handled by many Markdown processors -->
+        <x:variable name="in" as="xs:string" xml:space="preserve">    * list item one
+    * list item two
+    * list item three
+    * list item four
+      - item 4 subitem 1
+      - item 4 subitem 2</x:variable>
+        <x:call template="parse-markdown">
+            <x:param name="markdown-str" select="$in" />
+        </x:call>
+        <x:expect label="expressed as markup" select=".">
+            <ul>
+                <li>list item one</li>
+                <li>list item two</li>
+                <li>list item three</li>
+                <li>list item four<ul>
+                    <li>item 4 sub 1</li>
+                    <li>item 4 sub 2</li></ul>
+                </li>
+            </ul>
+        </x:expect>
+    </x:scenario>
+
+    <x:scenario label="OSCAL Issue #1151 but left flush, no gratuitous indenting">
+        <x:variable name="in" as="xs:string" xml:space="preserve">* list item one
+* list item two
+* list item three
+* list item four
+  - item 4 subitem 1
+  - item 4 subitem 2</x:variable>
+        <x:call template="parse-markdown">
+            <x:param name="markdown-str" select="$in" />
+        </x:call>
+        <x:expect label="expressed as markup" select=".">
+            <ul>
+                <li>list item one</li>
+                <li>list item two</li>
+                <li>list item three</li>
+                <li>list item four<ul>
+                    <li>item 4 sub 1</li>
+                    <li>item 4 sub 2</li></ul>
+                </li>
+            </ul>
+        </x:expect>
+    </x:scenario>
+</x:scenario>
+</x:description>
diff --git a/test-suite/metaschema-xspec/markdown-types/markup-mix.xspec b/test-suite/metaschema-xspec/markdown-types/markup-mix.xspec
new file mode 100644
index 000000000..b89911c38
--- /dev/null
+++ b/test-suite/metaschema-xspec/markdown-types/markup-mix.xspec
@@ -0,0 +1,39 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<x:description 
+    xmlns:x="http://www.jenitennison.com/xslt/xspec"
+    xmlns:xs="http://www.w3.org/2001/XMLSchema"
+    xmlns:m="http://csrc.nist.gov/ns/oscal/metaschema/1.0"
+    xmlns="http://csrc.nist.gov/ns/oscal/metaschema/1.0"
+    stylesheet="../../../toolchains/xslt-M4/converter-gen/xml-to-markdown.xsl"
+    run-as="external">
+    
+    <!-- For testing conversions from Markup to Markdown -->
+ 
+    <!-- source elements in metaschema namespace, which the XSLT matches
+        - this XSLT is cloned (not copied) into derivative converters -->
+    
+<x:scenario label="When converting markdown to markup">
+    
+    <x:scenario label="to show it works on a simple line of content">
+        <x:context mode="md">
+            <p>Here's some <em>paragraph</em> content.</p>
+        </x:context>
+        <x:expect label="one line shows a case of italic" xmlns="http://www.w3.org/2005/xpath-functions">
+            <string>Here's some *paragraph* content.</string>
+        </x:expect>
+    </x:scenario>
+    
+    <x:scenario label="and also working on a couple of lines">
+        <x:context mode="md">
+            <p>Here's some <em>paragraph</em> content.</p>
+            <p>And a <strong>second</strong> paragraph.</p>
+        </x:context>
+        <x:expect label="double-spaced lines show some italics and bold" xmlns="http://www.w3.org/2005/xpath-functions">
+            <string>Here's some *paragraph* content.</string>
+            <string/>
+            <string>And a **second** paragraph.</string>
+        </x:expect>
+    </x:scenario>
+    
+</x:scenario>
+</x:description>
diff --git a/test-suite/metaschema-xspec/markdown-types/readme.md b/test-suite/metaschema-xspec/markdown-types/readme.md
new file mode 100644
index 000000000..d1b9a4923
--- /dev/null
+++ b/test-suite/metaschema-xspec/markdown-types/readme.md
@@ -0,0 +1,17 @@
+# Metaschema processing XSpec testing - Markdown to Markup conversion and back
+
+Unit testing for Markdown processors supporting OSCAL Markdown.
+
+By defining edge cases, this aims to show a deterministic bidirectional mapping, or failing that a demonstration of where issues remain in defining or implementing such a mapping.
+
+
+To run XSpec, we suggest either an XML IDE or a command line tool as described in [XSpec documentation in Github](https://github.com/xspec/xspec/wiki).
+
+## Markdown to markup
+
+File `markdown-mix.xspec` has two simple (working) cases and one currently breaking case.
+
+## Markup to Markdown
+
+File `markup-mix.xspec` has two simple (working) cases for demonstration.
+
diff --git a/test-suite/oscal/v1.0.0/metaschema-browser.xsl b/toolchains/xslt-M4/util/metaschema-browser.xsl
similarity index 100%
rename from test-suite/oscal/v1.0.0/metaschema-browser.xsl
rename to toolchains/xslt-M4/util/metaschema-browser.xsl
diff --git a/test-suite/oscal/v1.0.0/metaschema-poll.xsl b/toolchains/xslt-M4/util/metaschema-poll.xsl
similarity index 100%
rename from test-suite/oscal/v1.0.0/metaschema-poll.xsl
rename to toolchains/xslt-M4/util/metaschema-poll.xsl