How can I use XSL to detect patterns in one XML file defined in another ?

I have two files :
1.  The data I'm given.
2.  The file I've created with the patterns I want to find.

An abridged example of the given data might be :
...

If the pattern data is:
...

The result would be :
<areas>
<area name="LAR 23">
<alarm equipment="1 Alarm" found="group-2" />
<alarm equipment="3 Alarm" found="group-2" />
<alarm equipment="MDU X2301 Relay fail"/>
<alarm equipment="2 Alarm" found="group-2" />
<alarm equipment="MDU X2301 Fuse fail"/>
</area>
...

You can see that a "found" attribute has been added wherever a pattern from the pattern file has been found. The pattern must be found in its entirety (ie LAR 51 doesn't find "group-2" as "2 Alarm" is not present). The order of items is unimportant (ie LAR 23 does find group-2 despite not being in the order it's defined in).

- Supplementary question.
Can this be extended to find patterns defined using regular expressions ?

~/t/ftemp $ cat groups.xml
<groups>
<group id="group-1">
<alarm equipment="Frame 1 PSU 1"/>
<alarm equipment="Frame 1 PSU 2"/>
<alarm equipment="Fan Tray 1"/>
</group>
<group id="group-2">
<alarm equipment="1 Alarm"/>
<alarm equipment="2 Alarm"/>
<alarm equipment="3 Alarm"/>
</group>
</groups>~/t
~/t/ftemp $ cat robert.xml
<areas>
<area name="LAR 23">
<alarm equipment="1 Alarm"/>
<alarm equipment="3 Alarm"/>
<alarm equipment="MDU X2301 Relay fail"/>
<alarm equipment="2 Alarm"/>
<alarm equipment="MDU X2301 Fuse fail"/>
</area>
<area name="LAR 41">
<alarm equipment="MDU X4107 Relay fail"/>
<alarm equipment="MDU X4107 Fuse fail"/>
<alarm equipment="MDU X4108 Relay fail"/>
<alarm equipment="MDU X4108 Fuse fail"/>
<alarm equipment="Frame 1 PSU 1"/>
<alarm equipment="Frame 1 PSU 2"/>
<alarm equipment="Fan Tray 1"/>
</area>
<area name="LAR 51">
<alarm equipment="1 Alarm"/>
<alarm equipment="3 Alarm"/>
<alarm equipment="Frame 1 PSU 1"/>
<alarm equipment="Frame 1 PSU 2"/>
<alarm equipment="Fan Tray 1"/>
</area>
<area name="LAR 53">
<alarm equipment="1 Alarm"/>
<alarm equipment="2 Alarm"/>
<alarm equipment="Rack 5308 Power Fail Alarm"/>
<alarm equipment="Rack 5309 Power Fail Alarm"/>
<alarm equipment="3 Alarm"/>
</area>
<area name="LAR63">
<alarm equipment="MDU X6311 Relay fail"/>
<alarm equipment="MDU X6311 Fuse fail"/>
</area>
</areas>~/t/ftemp $
~/t/ftemp $ xslt2 robert.xml robert.xsl
<?xml version="1.0" encoding="UTF-8"?><areas>
<area name="LAR 23">
<alarm equipment="1 Alarm" found="group-2"/>
<alarm equipment="3 Alarm" found="group-2"/>
<alarm equipment="MDU X2301 Relay fail"/>
<alarm equipment="2 Alarm" found="group-2"/>
<alarm equipment="MDU X2301 Fuse fail"/>
</area>
<area name="LAR 41">
<alarm equipment="MDU X4107 Relay fail"/>
<alarm equipment="MDU X4107 Fuse fail"/>
<alarm equipment="MDU X4108 Relay fail"/>
<alarm equipment="MDU X4108 Fuse fail"/>
<alarm equipment="Frame 1 PSU 1" found="group-1"/>
<alarm equipment="Frame 1 PSU 2" found="group-1"/>
<alarm equipment="Fan Tray 1" found="group-1"/>
</area>
<area name="LAR 51">
<alarm equipment="1 Alarm" found="group-2"/>
<alarm equipment="3 Alarm" found="group-2"/>
<alarm equipment="Frame 1 PSU 1" found="group-1"/>
<alarm equipment="Frame 1 PSU 2" found="group-1"/>
<alarm equipment="Fan Tray 1" found="group-1"/>
</area>
<area name="LAR 53">
<alarm equipment="1 Alarm" found="group-2"/>
<alarm equipment="2 Alarm" found="group-2"/>
<alarm equipment="Rack 5308 Power Fail Alarm"/>
<alarm equipment="Rack 5309 Power Fail Alarm"/>
<alarm equipment="3 Alarm" found="group-2"/>
</area>
<area name="LAR63">
<alarm equipment="MDU X6311 Relay fail"/>
<alarm equipment="MDU X6311 Fuse fail"/>
</area>
</areas>~/t/ftemp $
~/t/ftemp $ cat robert.xsl
<?xml version="1.0" encoding="US-ASCII"?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
                version="2.0">

<xsl:template match="alarm">
  <xsl:copy>
    <xsl:apply-templates select="@*"/>
    <xsl:for-each select="key('grouped',@equipment,doc('groups.xml'))">
      <xsl:attribute name="found" select="../@id"/>
    </xsl:for-each>
  </xsl:copy>
</xsl:template>

<xsl:template match="@*|node()"><!--identity for all other nodes-->
  <xsl:copy>
    <xsl:apply-templates select="@*|node()"/>
  </xsl:copy>
</xsl:template>

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