1. A computer-implemented system providing seller pre-qualification during the matching phase of an electronic commerce transaction, comprising: one or more seller databases including product data for one or more products; a computer coupled with the one or more seller databases and comprising a global content directory server, the global content directory comprising: a directory structure comprising a plurality of hierarchically organized product classes, each product class categorizing a plurality of products and defining one or more attributes of the products categorized in the product class; one or more pointers for each product class, each pointer identifying a corresponding seller database in which product data enabling a product transaction is stored for products categorized in the product class, each seller database associated with a seller having values for one or more seller attributes; and a search interface configured to communicate, in response to selection of a product class, automatic specification of one or more seller attribute criteria according to a buyer profile, and automatic specification of one or more product attribute criteria according to the buyer profile, a search query for product data only to one or more seller databases associated with sellers identified in the buyer profile and having seller attribute values matching the specified seller attribute criteria, these seller databases identified by the one or more pointers associated with the selected product class, the buyer profile comprising a list of prequalified sellers and seller attribute criteria compiled based on one or more previous search requests or one or more previous electronic transactions involving the buyer.