1. A method of data processing, comprising: providing access to an electronic database containing at least one of purchase order data sets and goods receipt data sets, the data sets including information about vendors and about goods obtained from the vendors; assembling a worklist from the information included in the data sets, the worklist defining a plurality of processing packages, each processing package being associated with an individual vendor and indicating one or more goods obtained from the vendor; and processing the plurality of processing packages of the worklist in a batch process using a processor, wherein during the batch process each processing package is processed to generate, in a trade preference processing context, a vendor declaration request for a particular vendor, the vendor declaration request listing the one or more goods obtained from the vendor and prompting the vendor to issue a vendor declaration for the one or more listed goods.