What are the 4 processes in slapd?

[bithead@bev.net (Matt Witherspoon)]

   The business I work for is currently considering using the OpenLDAP slapd, 
however the higher ups wanted a bunch of information on it. I figured most of 
it out except for one question, they wanted to know what each of the 4 
processes were for in slapd, like what each one does, and if it creates 
anymore at any time. I would try to figure out this myself but I'm not 
familiar with the C libraries for UNIX processes and threads. I was hoping a 
developer might know this right off the top of their head (this could make a 
decent FAQ too!). Thanks for any help!!

     ~Matt Witherspoon