Unpo

In a token ring network, the presence of a token (which is simply a particular bit setting) in a continually circulating transmission stream allows a device to change the bit setting (thus taking the token) and put a message in its place. The receiver of the message elsewhere in the token ring network removes the message and resets the bit setting (thus putting the token back) so that someone else in the ring of devices will be able to have a turn at using that message space.