Abstract: A two level document processing method which prepares a downstream document on the basis of an upstream document associated with software. The upstream document is one used by users of a software product or the like, and the downstream document is one used by designers of the software product or the like. The downstream document is prepared by comparing the upstream document with an upstream deletion document including information which is particular to the upstream document and is unnecessary for the downstream document (steps SA1-SA4), by continuing to search a deletion candidate to be eliminated from the upstream document until the last one, and by performing deletion/non-deletion of the deletion candidate from the upstream document in accordance with the results of the search (steps SA7-SA16). This makes it possible to improve efficiency of preparing a document, to refine the document, and to exploit potential information.

Abstract: A converter pressure control device for use in a converter waste gas disposing device wherein a calculator determines the difference between the pressure in a converter and atmospheric pressure and sets an operating parameter according to the detected difference. A pressure controller generates a control signal in accordance with the operating parameter and the difference in converter pressure and a predetermined value. The control signal is used to operate a damper to control the flow of waste gas through the converter.