title: Schematron conditional validation
body: <p>I've recently started using schematron to validate xml documents. I'm pretty impressed by it so far, but I've stumbled upon a rule that I can't get to work properly. </p>
  
  <p>I've made a simple example below. </p>
  
  <pre><code>&lt;iso:assert test="ns1:some-element/text() = 'false' and /ns1:same-other-element"&gt;Error message&lt;/iso:assert&gt;
  </code></pre>
  
  <p>Basically I want to validate two things, if <code>ns1:some-element/text()</code> contains 'false', <code>ns1:same-other-element</code> should be present, and that validation actually works. However, when <code>ns1:some-element/text()</code> contains something other than false, than I don't care weather ns1:same-other-element is there or not.</p>
  
  <p>At this moment, the rule also fires when ns1:same-other-element is missing and the value of <code>ns1:some-element/text()</code> is not 'false'</p>
  
  <p>Any ideas how to work around this?</p>