There are 5 available filters. They are used to filter on the Reference Table.
If Type is Comment this is Key Fields in the Comment Table.
If Type is Link this is Key Fields in Table with relation to the Links.
If Type is Codeunit this can be omitted. If desired it can be used by the Codeunit, as this have access to these values.
Look at the existing setup for samples.
Further information here.
See also
Reference
Comments SetupThis help includes both Dynamics NAV and Dynamics Business Central (BC). All references to NAV applies to both.