title: SVN : repository structure when 2 differents major version development in parallel?
body: <p>I am quite new with subversion, and I whant to know how to structure a repository.
  As I read, 'trunk' directory is for the main development, 'tags' is to snapshot a version, 'branches' is for doing some big changes/testing and not disturb the trunk.</p>
  
  <p>The problem is when one have two major versions to develop in parallel : I do not see very well how to structure that. I take the exemple of the python langage, both version 2 and 3 are under development, I see these structure possibilities :</p>
  
  <pre><code>1st one :
  ===========
  
  repos/
    python2/
      trunk/
      tags/
        V2.5/
        V2.6/
        V2.7/
      branches/
        big_modif1/
        testing2/
    python3/
      trunk/
      tags/
        V3.0/
        V3.1/
        V3.2/
      branches/
        big_modif43/
        testing37/
  
  2nd one :
  ===========
  
  repos/
    python/
      trunk/
        V2/
        V3/
      tags/
        V2.5/
        V2.6/
        V2.7/
        V3.0/
        V3.1/
        V3.2/
      branches/
        big_modif_on_v2.x/
        testing2_on_v2.x/
        big_modif43_on_v3.x/
        testing37_on_v3.x/
  
  3rd one :
  ===========
  
  repos/
    python/
      trunk/
      tags/
        V2.5/
        V2.6/
        V2.7/
        V3.0/
        V3.1/
        V3.2/
      branches/
        V2_trunk/
        V3_trunk/
        big_modif_on_v2.x/
        testing2_on_v2.x/
        big_modif43_on_v3.x/
        testing37_on_v3.x/
  </code></pre>
  
  <p>What will you choose (of course, you can propose something else) ?</p>