title: What is the best/correct/most efficient way to store a data series in XML
body: <p>I have an application which will store a series of (float) values in an XML file.  There could be upwards of 100,000 values so I am interested in keeping the size down, but I also want files to be readily accessible by third parties.  </p>
  
  <p>There seem to be various methods open to me as far as encoding the data within the XML:</p>
  
  <p>1.</p>
  
  <pre><code>&lt;data&gt;
    &lt;value&gt;12.34&lt;/value&gt;
    &lt;value&gt;56.78&lt;/value&gt;
    ...
    &lt;value&gt;90.12&lt;/value&gt;
  &lt;/data&gt;
  </code></pre>
  
  <p>2.</p>
  
  <pre><code>&lt;data&gt;
    &lt;value v="12.34"/&gt;
    &lt;value v="56.78"/&gt;
    ...
    &lt;value v="90.12"/&gt;
  &lt;/data&gt; 
  </code></pre>
  
  <p>3.</p>
  
  <pre><code>&lt;data&gt;12.34
  56.78
    ...
  90.12
  &lt;/data&gt; 
  </code></pre>
  
  <p>4.</p>
  
  <pre><code>&lt;data&gt;12.34, 56.78, ... 90.12&lt;/data&gt; 
  </code></pre>
  
  <p>and there are probably more variations as well.</p>
  
  <p>I'm just curious to know the drawbacks (if any) to each of these approaches.  Some may not be compliant for example.</p>