The standard distribution of Apache does not provide adequate means for user
tracking, and this module provides them. What it actually does:
+ if the user has provided the cookie header with the correct cookie-name,
the module writes this cookie in notes with the name uid_got (accordingly,
then it may be written to the log);
+ if the user has arrived without the required cookie, the module issues the
SetCookie header for him/her and writes the cookie thus issued in notes
with the name uid_set (and this may also be written to the log);
+ if built-in P3P support is included, the P3P header is also issued as the
Set-Cookie header is issued.
WWW: http://www.lexa.ru/programs/mod-uid-eng.html