Re: how to ask analyze-string for only one match?

This stylesheet does what you asked. Of course, I can't see the rest of the stylesheet to see if there are any other issues, but this should be the seed you need.

<?xml version="1.0" encoding="UTF-8" ?>
<xsl:stylesheet version="2.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:output method="xml" indent="yes" />
<xsl:strip-space elements="*" />

 <xsl:template match="/path">
   <xsl:analyze-string select="@d" regex="^M (\d+ )(\d+ )">
     <xsl:matching-substring>
       currentX=<xsl:value-of select="regex-group(1)"/>f;
       currentY=<xsl:value-of select="regex-group(2)"/>f;
     </xsl:matching-substring>
   </xsl:analyze-string>
 </xsl:template>

</xsl:stylesheet>