Erlang UUID Implementation
http://www.ietf.org/rfc/rfc4122.txt is the reference for official UUIDs. This implementation provides a version 1 UUID that includes the Erlang pid identifier (ID, Serial, Creation) within the 48 bit node ID. To make room for the Erlang pid identifier, the 48 bits from the MAC address are bitwise-XORed (i.e., 3 OCI (Organizationally Unique Identifier) bytes and 3 NIC (Network Interface Controller) specific bytes) down to 16 bits. The Erlang pid is bitwise-XORed from 72 bits down to 32 bits. The version 3 (MD5), version 4 (random), and version 5 (SHA) methods are provided as specified within the RFC.
Michael Truog (mjtruog [at] gmail (dot) com)