ColdFusion like UUID in PHP

Originally extracted from php.net with minor changes

The main function of an UUID is being unique. UUIDs are commonly use in databases to store a unique string, but not limited to. This function will help you to create a Coldfusion like Universally Unique Identifier (UUID) in PHP. This was customized for ColdFusion UUID format (8-4-4-16) .

UUID is a mix of 0-9 A-F Hex value.

function GenerateUUID() {
return sprintf('%04x%04x-%04x-%04x-%04x%04x%04x%04x',
  // 32 bits for "time_low"
 mt_rand(0, 0xffff), mt_rand(0, 0xffff),
  // 16 bits for "time_mid"
 mt_rand(0, 0xffff),
  // 16 bits for "time_hi_and_version",
  // four most significant bits holds version number 4
  mt_rand(0, 0x0fff) | 0x4000,
  // 16 bits, 8 bits for "clk_seq_hi_res",
  // 8 bits for "clk_seq_low",
  // two most significant bits holds zero and 

         // one for variant DCE1.1
  mt_rand(0, 0x3fff) | 0x8000,
  // 48 bits for "node"
  mt_rand(0, 0xffff), mt_rand(0, 0xffff), mt_rand(0, 0xffff)
 );
}