p:filter using p:with-option for select

Hi all,

Should it be possible to use p:with-option to specify the "select" 
option for p:filter?  I don't see anything in the specifications that 
says that would be invalid for this step; I expect it /does /say that 
somewhere, given that xml-calabash and Morgana both throw an error if I 
try it, it's just that I can't see where it says it.

The following works as expected:

<p:filter select="/*/greeting[3]" />

But if I use this variation, both xml-calabash and Morgana throw an error:

<p:filter>
     <p:with-option name="select" select="/*/greeting[3]" />
</p:filter>

The input is:

<greetings>
     <greetingxml:lang="cs">Ahoj světe!</greeting>
     <greetingxml:lang="de">Hallo Welt!</greeting>
     <greetingxml:lang="en">Hello, World!</greeting>
     <greetingxml:lang="es">¡Hola Mundo!</greeting>
     <greetingxml:lang="fr">Bonjour le monde!</greeting>
     <greetingxml:lang="it">Ciao mondo!</greeting>
     <greetingxml:lang="mi">Kia ora, e te Ao!</greeting>
     <greetingxml:lang="pt">Olá, mundo!</greeting>
     <greetingxml:lang="sv">Hej, Världen!</greeting>
</greetings>

And the error messages are:

   * From xml-calabash 3.0.20:

    Error:err:XD0030 atfile:/path/to/greeter.xpl:37:12: Step failed: Unexpected token "<eof>" at start of expression.

   * From MorganaXProcIIIee 1.7.6:

    <c:errors xmlns:c="http://www.w3.org/ns/xproc-step"><c:error code="err:XD0030" name="!1.1" type="p:filter" href="file:///path/to/greeter.xpl" line="49" column="12" xmlns:p="http://www.w3.org/ns/xproc" xmlns:err="http://www.w3.org/ns/xproc-error"><message>Error compiling XPath expression 'Hello, World!': Either nodetest or kindtest expected, butfound:EOF</message></c:error></c:errors>

Kind regards,

Sheila

Ps. In this case, I don't actually need to use p:with-option but tried 
it because I was getting a weird variable not declared error (now sorted 
using an AVT).  Now I'm just wondering whether it should work, in case I 
do need to use it in the future.