versions.js

// option 1 - "versions" key points to an array
{"versions":
  [
    {"version":{"id":...}},
    {"version":{"id":...}}
  ]
}

// option 2 - "version" key points to an array
{"versions":
  {
    "version":
      [{"id":...},
       {"id":...}]
  }
}

versions.php

# option 1
array (
  'versions' => 
  array (
    0 => 
    array (
      'version' => 
      array (
        'id' => '3',
      ),
    ),
    1 => 
    array (
      'version' => 
      array (
        'id' => '4',
      ),
    ),
  ),
)

# option 2
array (
  'versions' => 
  array (
    'version' => 
    array (
      0 => 
      array (
        'id' => '3',
      ),
      1 => 
      array (
        'id' => '4',
      ),
    ),
  ),
)