where could I find explanations of the messages on _vti_log/author

I will like to be able to understand the messages on the _vti_log/author.log,
for example.. .I have this:

[20 Apr 2006 14:35:43 -0500] NN.NNN.NNN.NNN username / [list documents] -
[20 Apr 2006 14:35:43 -0500] NN.NNN.NNN.NNN web - [url to web url] -
.....
[20 Apr 2006 15:07:35 -0500] NN.NNN.NNN.NNN username / [list documents] -
[20 Apr 2006 15:07:37 -0500] NN.NNN.NNN.NNN username / [get document]
dir/gl/dir/somefile.htm
[20 Apr 2006 15:07:38 -0500] NN.NNN.NNN.NNN username / [get web struct] -
[20 Apr 2006 15:29:10 -0500] NN.NNN.NNN.NNN web - [server version] -

where NN.NNN.NNN.NNN is always the same IP, username is the FP username for
this person and web is the user under which Apache runs.

why some of the entries have "web" as user???... and what it means "url to
web url" or why it needs to get "server version" ??? could it be that the
client has a webserver running in her box and FP thinks is a mirror???
(again... I don't know enough about MSWin servers)

I'm trying to see if reading this logs I can start understanding why when
this user works with her FP client server load goes to the roof... but when
another client does mostly the same... server load is not *so* impacted....

TIA
Marcos