When I monitor the gas mass flow rate at the outlet boundary, the title in the CSV file shows “Time”, “ep_g”. Also the auto-generated mfx file showsmonitor_ep_g(1)=.True.
The result seems to be the correct mass flow I needed but the title and auto-generated mfx file are confusing.
The header shows the variable used in the monitor. The monitor type, i.e, operator applied to the variable is common to all variables in the monitor. I would recommend using a descriptive filename for the monitor to keep track of the monitor type.