Do you have some images?
Blood chits were exactly that. They were issued to flyers in the hopes that, if they were downed behind enemy lines, the flyer could find someone sympathetic to him and give the person a blood chit. The chit was usually good for currency but only good if the airman was returned alive to U.S. or friendly forces.
www.armyairforces.com might be able to help you if the person was in the air corp.
You didn’t mention Vietnam but the usmcpress.com mentions the American flag being part of the “new” Chits during the Vietnam era:
During the war in Vietnam the fighter, attack, and helicopter crews carried new blood chits. These chits displayed the American flag, plus an appeal in 14 languages: English, Burmese, Thai, Old Chinese, New Chinese, Laotian, Cambodian, Tagalog, Vietnamese, Visayan, Malayan, French, Indonesian, and Dutch. The wording in each language was the same:
This website has a ton of info. It has a translation of the blood chits used by the 14th Air force who flew out of China during WW2. You maybe able to check the chinese symbols translated on the web page to the ones on your Uncle’s blood chit and see if they match.
http://cbi-theater-4.home.comcast.net/~cbi-theater-4/bloodchit/bloodchit.html
The sets consisted of five chits from five different theaters as follows:
Vietnam
China
Eastern European
European
Latin America
Yours is not the same as the Chinese set. This set had the languages of most of the areas near and around China. It also had an English translation of the text. Yours appears to be the same Chinese as in the Chinese set. It basically identifies the person who has the chit as an American military man who has inadvertently found himself in the readers area. It states that the bearer means no harm and is asking for assistance. If the readers helps this American military person, the military person will give him the flag to be taken to an embassy of the US for payment of services.
Unfortunately I am currently living in China and all my chits are in Thailand and in Minnesota. I gave most of them away to friends and as rewards for my subordinates in the AF when I was an officer (retired in 1994).
When I first saw the image of yours, I immediately thought it might be an old Flying Tiger one from Kunming. Not so. I have seen some, however, in Kunming that were custom made from that time period. Most of the Kunming ones were sewn onto the inside of the flight jackets. Pretty cool stuff if on can find these these days.
A 1991 retiree would mean that Kunming and Flying Tigers are out. Probably the chit was custom made from someplace. I had an assignment in Chang Rai in Northern Thailand where I was visiting someone at a local pub run by a French Foreign Legionnaire retiree. The legionnaire swore up and down that the chit he had on his wall was genuine. Wanted to beat me up for disagreeing with him. It was garbage and a poor copy to boot. He now has a real one hanging up on his wall courtesy of me.
Anyway, that is my history of chits. I did a lot of research on them when I had a bunch but that was in a different life. They no longer are issued and are not accounted or as far as I know of. I was not issued one when I flew from 1975 onward.
Hope this helps. I could have the Chinese translated by one of my students if you would really like it.