ExPath modules not available in Saxon HE

Cf. #43

Author: dariok

README.md

@@ -19,8 +19,13 @@ Paragraphs not having a defined outline level are not recognized as headings.**
 Build the package using `ant` on `build.xml`. You can upload docx files via a web form or by POSTing them to cnvert2.xql
 
 ### CLI
-To convert a docx, apply `docx.xsl` to `word-empty.xml` (or any XML file) and pass the parameter `filename` with a full 
-  URL to the docx to be converted.
+! The older `zip:xml-entry` function is available in Saxon ⩽ 9.5.1.1 while `file:read-binary` and `archive:extract-text`
+require Saxon *PE or EE* ⩾ 9.6. If you do not have Saxon PE or EE, you currently have to use a different XSLT processor,
+use oXygen (as it includes a recent version ofSaxon PE and EE), or use the web service implementation from within
+eXist-DB or baseX as these implement the ExPath modules independently.
+
+To convert a docx, apply `docx.xsl` to `word-empty.xml` (or any XML file) and pass the parameter `filename` with a path
+to the docx to be converted.
 
 ## How to use (XML to TEI)
 apply basic transformation scenario to docx or apply wt0.xsl and wt1.xsl to any flat Word XML

docx.xsl

@@ -11,17 +11,18 @@
   <xsl:param name="filename" />
 
   <xsl:variable name="zip">
-    <xsl:choose>
-      <xsl:when test="function-available('archive:extract-text')">
-        <xsl:sequence select="file:read-binary($filename)" />
-      </xsl:when>
-      <xsl:when test="function-available('zip:xml-entry')">
-        <xsl:value-of select="xs:anyURI($filename)"/>
-      </xsl:when>
-    </xsl:choose>
-  </xsl:variable> 
+    <xsl:sequence select="file:read-binary($filename)" use-when="function-available('archive:extract-text')" />
+    <xsl:value-of select="xs:anyURI($filename)" use-when="function-available('zip:xml-entry')" />
+    </xsl:variable> 
 
   <xsl:template match="/">
+    <xsl:if test="not(function-available('file:read-binary')) and not(function-available('zip:xml-entry'))">
+      <xsl:message terminate="yes">!!
+Neither file:read-binary nor zip:xml-entry functions are available. Word document
+cannot be extracted with this XSLT processor. zip:xml-entry is available in Saxon
+⩽ 9.5.1.1, file:read-binary requires Saxon PE or EE ⩾ 9.6.
+</xsl:message>
+    </xsl:if>
     <pkg:package
       xmlns:pkg="http://schemas.microsoft.com/office/2006/xmlPackage">
       <xsl:variable name="parts" select="('word/document.xml', 'word/comments.xml', 'word/endnotes.xml',