Is assignedBy needed for identifiers of vehicle and units in version 5.0.0?

[larsolofsson]

Is assignedBy needed for the following identifier types?

Vehicle

                        - IMONumber
                        - LicencePlateNumber
                        - RadioCallSign
                        - TrainNumber
                        - VesselName
                        - VoyageNumber

Units

                          - ContainerID
                          - CassetteID
                          - ISO6346ContainerNumber
                          # Don't use `assignedBy` with ISO6346ContainerNumber!
                          - LicencePlateNumber
                          - RailCarID
                          - RFTagSerialNumber
                          - SealNumber
                          - TrailerID
                          - VesselUnitID

Currently optional assignedBy,
- LogisticsSupplier
- Supplier
In XML papiNet has agency instead of assignedBy. An agency can specify what standard is used for the identifier, e.g. for a RailCarID.
The standard used could also be included in the name of the identifier type, e.g. ISO6346ContainerNumber.

Is type TrailerID needed?
Or will always LicencePlateNumber be used for trailers?

[larsolofsson]

See also #310