Source:http://linkedlifedata.com/resource/umls/id/C1708320
NCI: A number or token that lets a program access a resource. Programs often receive a handle in response to a request for a resource, and then they use the handle when they need to access the resource. When the program uses the handle, the value of the handle tells the system which resource, from the pool of resources maintained by the system, to use. (CSGNetwork's Online Computer, Telephony & Electronics Reference)