This invention describes a method for providing a subsequently revised input form, in which a prediction system selects at least one input form out of a number of input forms and displays them for the user to select. A user-definable categories feature allows customers andor merchants to define search queries for searching the electronic catalog, and to store these search queries under user-defined category names for subsequent use. One or more two way valves regulate and maintain inside pressure of the reactor and cooling and heating mechanisms are provided.