United States
US Armed Forces typically carry two identical oval tags containing:
USAF Format 1:
Surname, first name, middle initial
Social Security Number, followed by "AF" indicating branch of service.
Blood Group
"blank"
Religion
USAF Format 2:
Surname
First name and middle initial
Social Security Number, followed by "AF" indicating branch of service.
Blood Group
Religion
USMC:
Surname
First and middle initials,blood group
Social Security Number with no dashes and no spaces
Branch ("USMC"),Gas Mask size (S-small, M-medium, L-large)
Religious preference (or "NO PREFERENCE") or medical allergy if red medical tag.
US Navy:
Surname, first name, middle initial
"blank"
Social Security Number with no dashes or spaces followed immediately by branch blood group
"blank"
Religion
US Army:
Surname
First name, middle initial
Social Security Number
Blood type
Religion
USCG:
Surname, first name, middle initial
Social Security Number with no dashes or spaces followed immediately by branch
blood group
"blank"
Religion
Recently, the U.S. Army stopped using the term "Dog tags", replacing it with "I.D tags".
US Forces are also permitted to wear a small religious medallion, usually provided for them, on the smaller chain (e.g. a cross or Star of David). This provides a quick, easily identifiable reference for a chaplain should his services be required.
Copy from:
http://en.wikipedia.org/wiki/Dog_tag_(identifier)
