This article explains how containers are associated with a master bill of lading in the Vizion API.
Tracking containers by master bill of lading allows you to begin tracking containers associated with a master bill. Using the master bill to initiate a tracking acts as a look-up feature for the containers and does not track the master bill of lading itself.
Once all the containers associated with your master bill are found, each container will be tracked individually for the most current journey reported by the carrier. If a master bill tracking is initiated weeks after the journeys have been completed the containers may begin reporting the current journey and not the journey associated with the master bill.
A master bill of lading API end-point which tracks master bill journeys directly is on our roadmap. Please contact support if you have questions about this feature.