Apple Mac OS X Server (Upgrading and Migrating For Version 10.4 or Later) - Manual (Page 13)

Chapter 1 Before You Begin 13
Here is a list of the predefined group accounts:
Short name Group ID
nobody -2
nogroup -1
wheel 0
daemon 1
kmem 2
sys 3
tty 4
operator 5
mail 6
bin 7
staff 20
lp 26
postfix 27
postdrop 28
utmp 45
uucp 66
dialer 68
network 69
www 70
mysql 74
sshd 75
qtss 76
mailman 78
appserverusr 79
admin 80
appserveradm 81
clamav 82
amavisd 83
jabber 84
xgridcontroller 85
xgridagent 86
appowner 87
windowserver 88
accessibility 90
unknown 99