"grouping" tags

[wxdqz]

ive been meaning to write a "viewer" that groups tags by likeness, for instance these tags:

<Error>
<Type>File Not Found</Type>
<File>a.php</File>
<Date>14.2.07</Date>
</Error>

<Error>
<Type>Variable not found</Type>
<File>b.php</File>
<Date>12.2.07</Date>
</Error>

<Error>
<Type>File Not Found</Type>
<File>c.php</File>
<Date>13.2.07</Date>
</Error>

So in the final display it would show something like:
Error
- File Not Found
+ In file c.php on 13.2.07
+ In file a.php on 14.2.07
- Variable not found
+ In file b.php on 12.2.07


makes sense?

As you can see im a beginner in xml but any help will be appreciated.

thank you!