This invention relates to professional data management systems useful in the production of product specification documents such as prescriptions, service or parts orders, insurance contracts and the like that require detailed product and history information from multiple extensive information sources, especially remote heterogenous sources. More particularly, the invention relates to systems that assist professionals perform their everyday work in specifying customized technical products. A particularly preferred embodiment relates to a computer-implemented prescription management system to assist physicians in prescribing and reviewing drugs.