The package index in a shipment being tracked.
This property contains the index of a package contained in the shipment.
The PackageCount will contain the number of packages included in a shipment and the PackageIndex will contain the package index in the list of packages.
To retrieve all attributes corresponding to a package, the PackageIndex should be set from 0 to PackageCount - 1.
Currently, USPS does not support multiple package shipments and this does not apply.