'Additional Metric Filters' in line graph and advanced line graph widgets on FortiMonitor dashboards.
When creating one of these widgets, the dialog box offers the option 'Additional Metric Filters'.
This additional layer of filtering may be by tags or 'By Option String'.
The latter works with some agent based metrics, and calls for an explanation.
Agent metrics may represent more than one monitor-able datum.
For example a Windows disk space metric would have a different value for drive C:, D:, or whatever other logical disks are installed.
For a SQL metric one may want to specify a database name.
In such cases, the 'By Option String' field is used to specify the additional information, for example C: .
If the field is not populated, the widget will try to display the value for all options, e.g. disk space metrics for all disks.
This field only has an effect if the particular metric supports it.
In the future similar capabilities may be developed for non-agent metrics such as metrics collected via SNMP or the VMWare integration.
The basics of line graph and advanced line graph widgets for dashboards are described here: