easy one

I think this is probably easy for someone more knowledgeable than I am
in XSL - I have an XML document something like this:

<user>
    <name>Joe J# Jones</name>
    <phone>123-456-7890</phone>
    <ERR_name>Name may not contain invalid characters</ERR_name>
</user>

I'm working with one "user" here.  For the user, in an "if test" I want
to know if there are any node names within that "user" that start with
"ERR_" - how can I do that??

<xsl:if test="count(user[starts-with("ERR_

I can't seem to find the answer.  Anyone know this off the top of their
head?

TIA.

Hardy Merrill