Should information be encoded into identifiers?

["Costello, Roger L." <costello@mitre.org>]

Hi Folks,

Should identifiers be dumb? That is, no meaning can be ascribed to identifiers; they are completely random.

Or, should information be encoded into identifiers? What information should be encoded into them? 

There are precedents for encoding information into identifiers:

1. In the U.S. each auto is identified by a Vehicle Identification Number (VIN). Encoded within each VIN is a wealth of information, including the make and model of the auto, the plant where it was manufactured, and the vehicle's options.[1]

2. Books are identified by ISBNs. Encoded within each ISBN is a wealth of information, including the country, publisher, and the relative size of the publisher.[2]

3. UUIDs are used in many applications. Encoded within some UUIDs are the date/time stamp of when the UUID was created, and the network address of the machine which created the UUID.[3]

I suspect there are other examples of identifiers that have information encoded into them.

What are the advantages of encoding information into an identifier? What are the disadvantages?

/Roger

[1] Format of VIN: http://en.wikipedia.org/wiki/VIN

[2] Format of ISBN: http://www.xfront.com/isbn.xsd

[3] Fomat of UUID: http://www.ietf.org/rfc/rfc4122.txt