Comparing before and after records [SEC=UNCLASSIFI

Given this XML input

<?xml version="1.0" encoding="UTF-8"?>
<Events>
      <Before>
            <Event_Type>A</Event_Type>
            <Event_Field1>1111</Event_Field1>
            <Event_Field2>2222</Event_Field2>
            <Event_Field3>3333</Event_Field3>
            <EventId>1001</EventId>
      </Before>
      <Before>
            <Event_Type>B</Event_Type>
            <Event_Field1>1111</Event_Field1>
            <Event_Field2>2222</Event_Field2>
            <Event_Field3>3333</Event_Field3>
            <EventId>1002</EventId>
      </Before>
      <After>
            <Event_Type>A</Event_Type>
            <Event_Field1>1111</Event_Field1>
            <Event_Field2>2222</Event_Field2>
            <Event_Field3>3333</Event_Field3>
            <EventId>1001</EventId>
      </After>
      <After>
            <Event_Type>B</Event_Type>
            <Event_Field1>1111</Event_Field1>
            <Event_Field2>2233</Event_Field2>
            <Event_Field3>4444</Event_Field3>
            <EventId>1002</EventId>
      </After>
      <After>
            <Event_Type>A</Event_Type>
            <Event_Field1>1122</Event_Field1>
            <Event_Field2>2233</Event_Field2>
            <Event_Field3>3344</Event_Field3>
            <EventId>1003</EventId>
      </After>
</Events>

I need to output multiple XML files based on the number of unique
EventId's.  Filenames derived from {Event_Type}-{EventId}.xml.  Comments to
be generated

A-1001.xml
<?xml version="1.0" encoding="UTF-8"?>
<Event>
      <!-- unchanged -->
      <Field1>1111</Field1>
      <!-- unchanged -->
      <Field2>2222</Field2>
      <!-- unchanged -->
      <Field3>3333</Field3>
</Event>

B-1002.xml
<?xml version="1.0" encoding="UTF-8"?>
<Event>
      <!-- unchanged -->
      <Field1>1111</Field1>
      <!-- before: 2222 -->
      <Field2>2233</Field2>
      <!-- before: 3333 -->
      <Field3>4444</Field3>
</Event>

A-1003.xml
<?xml version="1.0" encoding="UTF-8"?>
<Event>
      <!-- new -->
      <Field1>1111</Field1>
      <!-- new -->
      <Field2>2233</Field2>
      <!-- new -->
      <Field3>4444</Field3>
</Event>

The creation of the multiple output document and the transformations are
easy.  The help I need is in comparing the <Before> and <After> contents
with the same <EventId>.

Thanks in advance,

Enrico Raymundo





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