diff --git a/README.md b/README.md
index 8e16839..0064b8c 100644
--- a/README.md
+++ b/README.md
@@ -22,7 +22,8 @@ Each post corresponds to a [subfolder under `src/`](https://github.com/galtm/xsp
 * [My XML Content in XSpec Causes an Error](https://github.com/galtm/xspectacles/tree/main/src/xml-content-error)
 * [One-or-More Ways to Foil Empty-Sequence Surprises in XSpec](https://github.com/galtm/xspectacles/tree/main/src/one-or-more)
 * [Overriding Global XSLT Variables in XSpec, Part 1](https://github.com/galtm/xspectacles/tree/main/src/override-global-var-part1)
-* **(NEW!)** [Overriding Global XSLT Variables in XSpec, Part 2](https://github.com/galtm/xspectacles/tree/main/src/override-global-var-part2)
+* [Overriding Global XSLT Variables in XSpec, Part 2](https://github.com/galtm/xspectacles/tree/main/src/override-global-var-part2)
+* **(NEW!)** [Overriding Global XSLT Variables in XSpec, Part 3](https://github.com/galtm/xspectacles/tree/main/src/override-global-var-part3)
 * [Saying "Almost Valid" or "Beyond Valid" in XSpec Tests for Schematron](https://github.com/galtm/xspectacles/tree/main/src/almost-valid)
 * [Saying "Not Yet" in XSpec](https://github.com/galtm/xspectacles/tree/main/src/pending)
 * [Saying "Whatever" in XSpec: How, Why, When](https://github.com/galtm/xspectacles/tree/main/src/three-dots)
diff --git a/src/override-global-var-part2/README.md b/src/override-global-var-part2/README.md
index d648b75..c105de0 100644
--- a/src/override-global-var-part2/README.md
+++ b/src/override-global-var-part2/README.md
@@ -4,7 +4,7 @@ Example files combining `run-as="external"` with `xsl:stylesheet/xsl:variable`:
 
 - `production-stylesheet.xsl`
 - `test-only-stylesheet.xsl`
-- `test-external-global.xspec`
+- `external_override-in-test-only-stylesheet.xspec`
 
 #### Links to Topic
 [Overriding Global XSLT Variables in XSpec, Part 2](https://medium.com/@xspectacles/overriding-global-xslt-variables-in-xspec-part-2-31829081f982)
diff --git a/src/override-global-var-part2/test-external-global.xspec b/src/override-global-var-part2/external_override-in-test-only-stylesheet.xspec
similarity index 100%
rename from src/override-global-var-part2/test-external-global.xspec
rename to src/override-global-var-part2/external_override-in-test-only-stylesheet.xspec
diff --git a/src/override-global-var-part3/README.md b/src/override-global-var-part3/README.md
new file mode 100644
index 0000000..9110836
--- /dev/null
+++ b/src/override-global-var-part3/README.md
@@ -0,0 +1,11 @@
+# Sample code for "Overriding Global XSLT Variables in XSpec, Part 3"
+
+Example files combining `run-as="external"` with `xsl:package/xsl:variable`:
+
+- `production-pkg/production-pkg.xsl`
+- `test-only-pkg/test-only-pkg.xsl`
+- `config.xml`
+- `external_override-in-test-only-pkg.xspec`
+
+#### Links to Topic
+[Overriding Global XSLT Variables in XSpec, Part 3](https://medium.com/@xspectacles/overriding-global-xslt-variables-in-xspec-part-3-545205cef963)
diff --git a/src/override-global-var-part3/config.xml b/src/override-global-var-part3/config.xml
new file mode 100644
index 0000000..bdbcbe9
--- /dev/null
+++ b/src/override-global-var-part3/config.xml
@@ -0,0 +1,16 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+  Sample Code for "Overriding Global XSLT Variables in XSpec, Part 3"
+  https://medium.com/@xspectacles/overriding-global-xslt-variables-in-xspec-part-3-545205cef963
+-->
+<configuration xmlns="http://saxon.sf.net/ns/configuration">
+  <xsltPackages>
+    <package name="urn:x-xspectacles:pkgs:production-pkg"
+      version="1.0"
+      sourceLocation="production-pkg/production-pkg.xsl"/>
+    <package name="urn:x-xspectacles:pkgs:test-only-pkg"
+      version="1.0"
+      sourceLocation="test-only-pkg/test-only-pkg.xsl"/>
+  </xsltPackages>
+</configuration>
+<!-- Copyright © 2024 by Amanda Galtman. -->
diff --git a/src/override-global-var-part3/external_override-in-test-only-pkg.xspec b/src/override-global-var-part3/external_override-in-test-only-pkg.xspec
new file mode 100644
index 0000000..d2c052f
--- /dev/null
+++ b/src/override-global-var-part3/external_override-in-test-only-pkg.xspec
@@ -0,0 +1,32 @@
+<?xml version="1.0" encoding="UTF-8" ?>
+<x:description run-as="external"
+  stylesheet="test-only-pkg/test-only-pkg.xsl"
+  xslt-version="3.0"
+  xmlns:x="http://www.jenitennison.com/xslt/xspec">
+
+  <!--
+    Sample Code for "Overriding Global XSLT Variables in XSpec, Part 3"
+    https://medium.com/@xspectacles/overriding-global-xslt-variables-in-xspec-part-3-545205cef963
+  -->
+
+  <x:variable name="x:saxon-config" href="config.xml"/>
+  <x:scenario>
+    <x:label>
+      Test-only package overrides global xsl:variable as xsl:param
+      during external transformation to test an XSLT package
+    </x:label>
+    <x:scenario label="With x:param, template uses">
+      <x:param name="my-param" select="'from x:param'"/>
+      <x:param name="data-file-name" select="'test-data1.xml'"/>
+      <x:call template="show-values-of-globals"/>
+      <x:expect label="the provided values"
+        select="('from x:param', 'test-data1.xml')"/>
+    </x:scenario>
+    <x:scenario label="Without x:param, template uses">
+      <x:call template="show-values-of-globals"/>
+      <x:expect label="values from production and xsl:override"
+        select="('from production', 'test-data-from-override.xml')"/>
+    </x:scenario>
+  </x:scenario>
+</x:description>
+<!-- Copyright © 2024 by Amanda Galtman. -->
diff --git a/src/override-global-var-part3/production-pkg/production-pkg.xsl b/src/override-global-var-part3/production-pkg/production-pkg.xsl
new file mode 100644
index 0000000..a21331b
--- /dev/null
+++ b/src/override-global-var-part3/production-pkg/production-pkg.xsl
@@ -0,0 +1,22 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<xsl:package name="urn:x-xspectacles:pkgs:production-pkg"
+  package-version="1.0" version="3.0"
+  xmlns:xs="http://www.w3.org/2001/XMLSchema"
+  xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
+
+  <!--
+    Sample Code for "Overriding Global XSLT Variables in XSpec, Part 3"
+    https://medium.com/@xspectacles/overriding-global-xslt-variables-in-xspec-part-3-545205cef963
+  -->
+
+  <xsl:param name="my-param" as="xs:string"
+    select="'from production'"/>
+  <xsl:variable name="data-file-name" as="xs:string"
+    select="'production.xml'" visibility="public"/>
+
+  <xsl:template name="show-values-of-globals" visibility="public">
+    <xsl:sequence select="($my-param, $data-file-name)"/>
+  </xsl:template>
+
+</xsl:package>
+<!-- Copyright © 2024 by Amanda Galtman. -->
diff --git a/src/override-global-var-part3/test-only-pkg/test-only-pkg.xsl b/src/override-global-var-part3/test-only-pkg/test-only-pkg.xsl
new file mode 100644
index 0000000..7a3442e
--- /dev/null
+++ b/src/override-global-var-part3/test-only-pkg/test-only-pkg.xsl
@@ -0,0 +1,24 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<xsl:package name="urn:x-xspectacles:pkgs:test-only-pkg"
+  package-version="1.0" version="3.0"
+  xmlns:xs="http://www.w3.org/2001/XMLSchema"
+  xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
+
+  <!--
+    Sample Code for "Overriding Global XSLT Variables in XSpec, Part 3"
+    https://medium.com/@xspectacles/overriding-global-xslt-variables-in-xspec-part-3-545205cef963
+  -->
+
+  <xsl:use-package name="urn:x-xspectacles:pkgs:production-pkg"
+    version="1.0">    
+    <xsl:accept component="template" names="show-values-of-globals"
+      visibility="public"/>    
+    <xsl:override>
+      <!-- Override xsl:variable with xsl:param -->
+      <xsl:param name="data-file-name" as="xs:string"
+        select="'test-data-from-override.xml'"/>
+    </xsl:override>
+  </xsl:use-package>
+
+</xsl:package>
+<!-- Copyright © 2024 by Amanda Galtman. -->