A quorum notice is a public posting made when three or more members of a body are expected to be in the same place at an event the body did not call. It exists because of the OpenMeetingLaw: the presence of a majority can turn a social occasion into a meeting.
The CityClerk's office posts notices for the CityCommission when it learns of invitations or upcoming events. The City is explicit that a quorum can also happen by accident, and that at such gatherings there is no agenda, no deliberation, no decision and no minutes.
Standing notices posted by the City include the Rotary Club of Great Falls, Tuesdays at noon at Meadowlark Country Club, and the Military-Community Relations Breakfast between Malmstrom Air Force Base, the Montana Air National Guard and City leadership, the second Wednesday of the month at 7:00 am.
Several boards post their own. The MansfieldCenterAdvisoryBoard notes that a quorum of its members may be present at public events held in the Mansfield Center, and that board business is not discussed at them. The NeighborhoodCouncils post notices whenever three or more council members gather.
Commission quorum notices: https://greatfallsmt.gov/258/Quorum-Notices Neighborhood council quorum notices: https://greatfallsmt.gov/276/Quorum-Notices