title: XSLT: Change certain attribute values
body: <p>I am a XSLT newbie and have a simple task:</p>
  
  <p>Suppose I have the following XML:</p>
  
  <blockquote>
  <pre><code>&lt;Element1&gt;
      &lt;Element2 attr1="1"/&gt;
  &lt;/Element1&gt;
  &lt;Element1 attr1="2"/&gt;
  &lt;Element1&gt;
      &lt;Element2 attr1="2"/&gt;
  &lt;/Element1&gt;
  </code></pre>
  </blockquote>
  
  <p>I want to transform the XML to the same XML with one change: All attributes named "attr1" no matter where they are have to be transformed so that for example "1" will be "A" and "2" will be "X", i. e. to</p>
  
  <blockquote>
  <pre><code>&lt;Element1&gt;
      &lt;Element2 attr1="A"/&gt;
  &lt;/Element1&gt;
  &lt;Element1 attr1="X"/&gt;
  &lt;Element1&gt;
      &lt;Element2 attr1="X"/&gt;
  &lt;/Element1&gt;
  </code></pre>
  </blockquote>
  
  <p>How can I achieve this?
  Thanks in advance!</p>