In previous columns, we have discussed many of the basics of preparing the data for a computerized file. We have stressed being sure that the editorial policy and individual rules are set consistently so that the data may be easily retrieved once it is entered into that big black box called the computer. The next and very important step is computerization of the data, or converting already-computerized data to match the specifications of the hardware and software system you are going to run your file on--an exciting but exacting task. The data can be made to match your machine by using photocomposition tapes, MARC tapes, floppies, hard disks, paper, forms, catalog cards, brochures, and any number of other information sources.