Read the spec for the contains() function - it doesn't do what you think.
You have guessed wrongly that it takes as input a set of nodes and returns
true if any of those nodes is equal to the second argument. What it actually
does is to take a single string as input and return true if that string
contains a specified substring.

Also, read the error message. It tells you very explicitly what you have
done wrong: contains requires a single item as the value of the first
argument, and you have supplied a sequence of values. If your XML had been
ill-formed, the message would have been completely different.

If you want to test whether any topic is equal to XML, use <xsl:if
test="//topic[. = 'XML']"/>. If you want to test whether any topic has "XML"
as a substring, use <xsl:if test="//topic[contains(., 'XML')"/>. 

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

> -----Original Message-----
> From: Alice Wei [mailto:ajwei@xxxxxxxxxxx] 
> Sent: 17 December 2007 03:38
> To: xsl-list
> Subject:  No Duplicate Contain() is Allowed?
> 
> Dear all:
> 
>     For those of you who may know something about SQL or 
> XQuery might be able to help me out.
> 
> XML:
>       <bookshelf>
>       <book>XSLT 2.0: From Beginning to Professional
>         <topic>XML</topic>
>        <publisher>Wiley</publisher></book>
>       <book>XML in a Nutshell
>       <publisher>Oreilly</publisher</book>
>       <book>XSLT 2.0: Programmer's Reference
>       <topic>XML</topic>
>       <publisher>Wrox</publisher>
>       </book>
>       </bookshelf>
> 
> XSLT:
> 
> <xsl:template match="bookshelf">
> 
>         <xsl:if test="contains(//book/*, 'XML')">
>             <xsl:apply-templates/>
>         </xsl:if>
>        <xsl:if test="contains(//topic/*, 'XML')">
>           <xsl:apply-templates/>
>       </xsl:if>
> </xsl:template>
> 
> 
> What happened is really weird. If I had commented out the 2nd 
> <xsl:if> statement, it brings back one line without error. 
> When I got to the 2nd one, it tells me this error: 
> Description: A sequence of more than one item is not allowed 
> as the first argument of contains() ("", "", ...)
> 
> My document is obviously well-formed, can anyone please give 
> me some suggestions on how to get rid of this error?
> 
> Thanks to those who can help.
> 
> Alice
> 
> 
> Alice Wei
> MIS 2008
> School of Library and Information Science Indiana University 
> Bloomington