A Globally Unique Identifier (GUID) is a 128-bit number that is generated by a special algorithm and is virtually guaranteed a to be unique in the world. That is to say that every GUID generated by this algorithm is different from any other.

Dyalog APL properties that represent GUIDs are read-only character vectors that represent the GUID as a string of hexadecimal digits wrapped in braces.

For example "{3B7C8860-D78F-101B-B9B5-04021C009402}".