1. A method of pre-qualifying sellers during the matching phase of an electronic commerce transaction, comprising: making accessible to at least one buyer computer a directory structure comprising a plurality of hierarchically organized product classes, wherein the directory structure is associated with a global content directory server and the global content directory server is coupled with one or more seller databases, 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 being provided for each product class, each pointer identifying a 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 communicating, by the at least one buyer computer, in response to selection of a product class and specification of one or more seller attribute criteria, a search query for product data only to one or more seller databases associated with sellers having seller attribute values matching the specified seller attribute criteria, these seller databases being identified by the one or more pointers associated with the selected product class.