If Type is Comment this is not filled in.
If Type is Link this is not filled in.
If Type is Codeunit fill in the Object Number.
Further information here.
By using Codeunit one avoids changes to JobManager objects, making updating JobManager versions much easier. The installation package for JobManager contains some examples.
See also
Reference
Comments SetupThis help includes both Dynamics NAV and Dynamics Business Central (BC). All references to NAV applies to both.