screen program information

[Ardaman Chauhan TDC]

Greetings All :
          This is the first time i am posting to the net so please
excuse me if i goof up.
          I downloaded the screen program from the net a while back and
found it very useful.  I have a question about the detach/attach feature
of the program by which you can detach a process and after wards
reattach to the same process from some other terminal/login.
          Could somebody be kind enough to explain me the basic idea
about that feature, how it is implemented (main points).  The source
doesnot have many comments.  I have asked because an enquiring mind
wants to know.  I am a regular reader of this forum, so you can send me
the response or if you think suitable, post to the forum.
          Thanks in advance Ardaman S.  Chauhan TSDC Chauhan -at
system-m.bull.com