Noun
A notice carried by military personnel, addressed to any civilians who may come across them when they are in trouble, requesting that assistance be offered to them in such situations.
A form signed by a passenger on a private or military aircraft, granting indemnity to the flight operator against any accident.
Source: en.wiktionary.orgApplications Blood chit used by WWII US pilots fighting in China, in case they were shot down by the Japanese. Source: Internet