text: (Globally Unique IDentifier) An implementation of the universally unique ID (see UUID) that is computed by Windows and Windows applications. Using a pseudo-random 128-bit number, GUIDs are used to identify user accounts, documents, software, hardware, software interfaces, sessions, database keys and other items.
  First developed to keep track of instances of COM objects, GUIDs were created by an algorithm that used the MAC address of the local Ethernet card. Microsoft later dropped the Ethernet address due to protests that documents could be traced back to a particular user's machine. Following are common Microsoft GUIDs.
  Type Used For AppID Applications CLSID COM object classes IID Interfaces MID Machines OID Objects SETID Set of objects
  Other GUIDs
  Other types of identifiers are also called GUIDs; for example, Atom feeds and some RSS feeds contain unique text-based numbers for each blog post. See Atom syndication format, UUID and OID.
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  A globally unique identifier (GUID, /ˈɡwɪd/ or
  /ˈɡuːɪd/) is a unique reference number used as an identifier in computer software. The term GUID also is used by various implementations; however, GUID numbers are not always generated randomly.[1]
  A GUID can be stored as a 16-byte (128-bit) number, which is usually split into four fields. The UUID standards [2] [3] state that all four fields must be encoded with the most significant byte first (i.e. Big-Endian). However, the reference for a commonly[4] used structure of the data type doesn't mention byte ordering.
  One to three of the most significant bits of the second byte in Data 4 define the type variant of the GUID:
  The most significant four bits of Data3 define the version number, and the algorithm used.'s treated differently than in the structure.
  Often braces are added to enclose the above format, as such:
  When printing fewer characters is desired, GUIDs are sometimes encoded into a base64 or Ascii85 string.
  A base64-encoded GUID consists of 22 to 24 characters (depending on padding), for instance:
  and Ascii85 encoding gives 20 characters, for example:
  In Uniform Resource Names (URN), the v1 GUIDs have namespace identifier "uuid", e first technique, described by Jimmy Nilsson in August 2002[7] version 2005, Microsoft added a function to the Transact-SQL language called NEWSEQUENTIALID(),[8].[9]
  In the Windows registry, in the key sequence "My Computer\HKEY_Classes_Root\CLSID", the DAO.[citation needed]. Atom's IDs need to be valid URIs (usually URLs pointing to the entry, or URNs containing any other unique identifier).
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