File _constraints of Package blender

<constraints>
  <hardware>
   <disk>
    <size unit="G">20</size>
   </disk>
   <physicalmemory>
      <size unit="M">1024</size>
   </physicalmemory>
   <memory>
      <size unit="M">2048</size>
   </memory>
  </hardware>
</constraints>