[TUHS] historical users and groups

Trying to understand some users and groups that continue to exist on BSD systems. Can someone please point me to references or share examples of historical and/or recent uses of the following users and groups? Also any clarifications of my understandings below would be appreciated. (My context is BSD. I know some of these may have different old and existing uses on other systems.) daemon user I see /var/msgs on NetBSD is owned by daemon. msgs will abort if doing -c (cleanup) if not root or daemon user. I guess that is historic. I don't see any daemon user usage. operator user I understand that historically, the operator user had logins for those doing disk backups (via its login group privileges). I understand the operator group, just wondering if any recent uses of operator user. bin user Don't know what uses it. daemon group I understand that historically, these are for processes needing less privileges than the wheel group. Also historically, programs using /var/spool directories were setgid daemon. Anything common other than LPD/LPR still use the daemon group? sys group I understand that historically, the sys group was used for access to the kernel (/sys?) sources. (I don't know if that was just read or was for writing too.) Anyone still use "sys" group? (I guess this is like wsrc which sometimes I manually setup and use for writing to src directories.) bin group I understand that historically, used as the group for system binaries, but commonly the wheel group is used instead. Some third-party software, like OpenOffice.org, install files owned by the bin group. staff group How would this differ from wheel or operators? Any recent systems actually have default use of this? guest group Any recent systems actually have default use of this? nobody group versus nogroup group What is the significance of having both of these groups? Thanks!