[stunnel-users] Definition of accept/local/remote sockets

Is there a clear definition of what stunnel defines as the accept, local, and remote sockets below?

socket = a|l|r:OPTION=VALUE[:VALUE] Set an option on accept/local/remote socket

From: http://www.stunnel.org/static/stunnel.html It seems to me that the accept and local socket would be the same thing. Thanks, Dave