This optional key is used to specify Mach services to be registered with the Mach bootstrap sub-system. Each key in this dictionary should be the name of service to be advertised. The value of the key must be a boolean and set to true. Alternatively, a dictionary can be used instead of a simple true value.
Finally, for the job itself, the values will be replaced with Mach ports at the time of check-in with launchd.