Shipment Tracking meta key

HI there,

I am trying to integrate another plugin that prints the entered shipping details and prints a label.

I am in need of the specific meta key for this plug-in shipment tracking so that it can be passed to the other plugin.

I am not so savvy in exploring the plugin code to find this, if you could possibly tell me what it is i would appreciate it.

Please see picture attached of the other plugin and where i must enter this meta key.

Regads,
martin.