I would do it as in XSLT 1.0:

test="//id[number(substring-after('ttt:')) = $a]"

Michael Kay
http://www.saxonica.com/ 

> -----Original Message-----
> From: tom tom [mailto:tomxsllist@xxxxxxxxxxx] 
> Sent: 03 July 2007 20:28
> To: xsl-list@xxxxxxxxxxxxxxxxxxxxxx
> Subject:  Converting a string to a double
> 
> Hi all,
> 
> Using the following XML:
> 
> <i>
>    <b>
>       <id>urn:ttt:188589</id>
>    </b>
>    <b>
>       <id>urn:ttt:188689</id>
>    </b>
>    <b>
>       <id>urn:ttt:188989</id>
>    </b>
> </i>
> 
> I want to see if the document contains an id tag with a 
> particular number after the string 'ttt:' I can only do this 
> by comparing this value with a double datatype value stored 
> in a variable $a. What is the best way to do this in XSLT 2?
> 
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