How to prohibit leading and traling whitespace in XML Schema

Question

I want to prohibit the use of leading and trailing whitespace in an element but besides that all other content is allowed.
For examble <   word? > should give a validation error.
I do not want to use
<whiteSpace value="collapse"/>
Because it doesn't give a validation error.
Is it possible to make a pattern og in some other way solve my problem?
Thanks in advance, Martin

Answer 1

Here is an example schema snippet (not a complete schema!) that does what you want I think, using a regular expresssion pattern, allowing one or more non-white-space characters followed by an optional sequence of any character followed by one or more non-white-space characters:
Code Snippet
        <xs:element name="foo" maxOccurs="unbounded">
          <xs:simpleType>
            <xs:restriction base="xs:string">
              <xs:pattern value="\S+(.*\S+)*"/>
            </xs:restriction>
          </xs:simpleType>
        </xs:element>
Here are some example elements with valid contents:
Code Snippet
  <foo>a</foo>
  <foo>a b</foo>
  <foo>a b c d e f g</foo>
And here some elements with invalid contents that validation would catch:
Code Snippet
  <foo> a</foo>
  <foo>a </foo>