UUID (Universally Unique Identifier), also known as GUID (Globally Unique Identifier) represents a 128-bit long value that is unique for all practical purposes. The standard representation of the UUID uses hex digits (octets):

<script>
    var uuid = new Ax.util.UUID();
    console.log(uuid);
</script>

23e4567-e89b-12d3-a456-556642440000

A UUID is made of up of hex digits (4 chars each) along with 4 “-” symbols which make its length equal to 36 characters.