Existing Wording: In a few special cases, humans customarily use codes directly for elements that have type

"string". A typical case is codes for states, and there are several places where a URIs must

come from a set of controlled values. An element of type string (datatypes.html#string) or uri

(datatypes.html#uri) can also be bound to a value set. When a string or uri is bound to a value

set, the value property SHALL contain the code specified by the value set, and the system and

display values are ignored.

Comment:

when you look closely at these they are data bases with multiple fields. and the short string is the code to get to these

Don't treat these specially just because there is no numeric or none sense code

State /Abbreviation /Postal Code

Alabama Ala. AL

Alaska Alaska AK

American Samoa AS

Arizona Ariz. AZ

Arkansas Ark. AR

California Calif. CA

Colorado Colo. CO

Connecticut Conn. CT

Delaware Del. DE

Dist. of Columbia D.C. DC

Florida Fla. FL

Georgia Ga. GA

Guam Guam GU

Hawaii Hawaii HI

Read more: U.S. State Abbreviations & State Postal Codes http://www.infoplease.com/ipa/A0110468.html#ixzz3Z6G7shv9 o