Must XML schema elements by imported in WSDL 2.0?

The following question arose while developing Woden [1].

Assertion Schema-0016 (from section 3.1) states:

"A WSDL 2.0 document MUST NOT refer to XML Schema components in a given 
namespace unless an xs:import or xs:schema element information item for 
that namespace is present or the namespace is the XML Schema namespace 
which contains built-in types as defined in XML Schema Part 2: Datatypes 
Second Edition [XML Schema: Datatypes]."

The end of the sentence, "...which contains built-in types..." seems to 
imply that only XML Schema types are implicitly available in WSDL 2.0. Are 
schema elements also implicitly available in WSDL 2.0? For example, if I 
want to define an input as follows

<wsdl:input element="xsd:schema" />

do I need to import the schema namespace?

If the answer is yes, I suggest the assertion text be modified to 
explicitly state that the schema namespace must be imported if schema 
elements are to be used. As a suggestion,
"...XML Schema namespace and an XML Schema type has been referenced. XML 
Schema contains..."
If the answer is no, I suggest the assertion text be modified to make it 
clear that both elements and types are available. As a suggestion,
"...which contains elements and built-in types...".

[1] http://incubator.apache.org/woden

Thanks,

Lawrence Mandel

Software Developer
IBM Rational Software
Phone: 905 - 413 - 3814   Fax: 905 - 413 - 4920
lmandel@ca.ibm.com