Getting equivalence classes on attributes

Hello.  Is there a way to write an XPath expression that will return each
equivalence class on the value of an attribute, i.e. every collection of
nodes whose value for a certain attribute are the same e.g.

<foo att="bar"/>

<foo att="bar" att2="quux"/>

<blah att="bar"/>

<foo att="baz"/>

<foo att="quux"/>

The first three elements would belong to one equivalence class on the
attribute 'att', while the fourth would belong to another, and the fifth
to yet another.  I would want an XPath expression that would return each
of these equivalence classes.  Is this possible?

--
Rafael R. Sevilla <sevillar@xxxxxxxxxxxxxxxxx>   +63(2)   8177746 ext. 8311
Programmer, InterdotNet Philippines              +63(917) 4458925
http://dido.engr.internet.org.ph/

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