The secret behind GUID

• The user's network card MAC address is used as a base for the last group of GUID digits
• Using GUID, a document can be tracked back to the computer that created it
• This privacy hole was used when locating the creator of the Melissa worm
• Most of the other digits are based on the time while generating the GUID.

• GUIDs which contain a MAC address and time can be identified by the digit "1" in the first position of the third group of digits, for example
  

{2f1e4fc0-81fd-11da-9156-00036a0f876a}.

Have fun with GUID :)