A UUID (user-definable LUN identifier) is typically composed of a Prefix and an Initial Number.

The following rules apply to defining a UUID:

• These characters cannot be used for a UUID: \ / : , ; * ? " < > |
• A space character cannot be used as the first or the last character of a UUID.
• UUIDs are case-sensitive. For example, Abc and abc are different UUIDs.

Also note the following when defining a UUID:

• If host mode 05 OpenVMS is used with host mode option 33 set to ON, LUs that do not have UUID settings are inaccessible.
• If host mode 05 OpenVMS is used with host mode option 33 set to OFF, LUs that have UUID settings are inaccessible.
• For an OpenVMS server host, the Prefix can include up to 5 digits, from 1 to 32767, and the Initial Number can include up to 5 digits, from 0 to 32767.
• For a server host other than OpenVMS, the Prefix can include up to 64 ASCII characters (letters, numerals and symbols) and the Initial Number can include up to 9 digits.