title: What is "size" in flare json -- used in D3 examples?
body: <p>My colleague and I are working with a D3 visualization. Specifically we are starting with <a href="http://bl.ocks.org/mbostock/4063530" rel="nofollow">this example</a>. This visualization appears to use some kind of json related to the  <a href="http://flare.prefuse.org/api/" rel="nofollow">flare API</a></p>
  
  <p>In the sample json, there's lines like:</p>
  
  <pre><code> "name": "cluster",
   "children": [
    {"name": "AgglomerativeCluster", "size": 3938},
    {"name": "CommunityStructure", "size": 3812},
    {"name": "HierarchicalCluster", "size": 6714},
    {"name": "MergeEdge", "size": 743}
  </code></pre>
  
  <p>I understand that stuff after "name" relates to a Flare class. What I can't seem to find, despite lots of googling, is what exactly "size" is and what its units are? More generally, where can one find some kind of specification on flare's json format and what it means?</p>