title: What is the meaning of conda's build string?
body: <p>If I run <code>conda info sphinx</code> from the command line, the last entry as of August 24, 2017, is </p>
  
  <pre><code>sphinx 1.6.3 py36_0
  -------------------
  file name   : sphinx-1.6.3-py36_0.tar.bz2
  name        : sphinx
  version     : 1.6.3
  build string: py36_0
  ...
  </code></pre>
  
  <p>What is the meaning of the  build string, which is mirrored above in the package version? Is this the minimum version of the python interpereter required by a package?</p>