Abstract: A system includes a web server having a server storage component including web page information, a rules engine, and a plurality of rules, and a client processor communicating with the web server over a global communication network. The client processor includes a processor component, a web browser, a web browser plug-in tool, and a processor storage component storing copies of the web page information, the rules engine, and the rules as downloaded from the server. The server embeds at least one of the rules engine and the rules with the web page information for download to the client processor. The rules establish a single valid data entry for a selected field of a web page for each combination of values for designated other fields of the web page. The rules engine executes the rules to select the single valid data entry dependent upon the values of the designated other fields.