An inventive procurement system includes a requisition system for special item purchases that are not found when searching a catalog database. Using the requisition system the buyer is provided with the desired item while the information associated with the requisition is selectively added to a rule-based knowledge base as well as to an item database. In a preferred embodiment a common language generator has been used to normalize free form data using pre-determined rules to place the data into a class/attribute/value relationship. By having the item requisition follow the same relationship, the pre-determined rules may be updated and the free-form data associated with the item properly coded for inclusion into an item database.