The claimed invention relates to a submersible direct-current electric motor to be used, in particular, for driving a submersible pump in downhole oil production. The array is arranged as three columns of one-half hour in duration, and twelve rows of program listings. The energy balance thus provides an accurate indication of the correct amount of energy needed, which is sufficient to operate the medical device properly, but without causing undue temperature rise. In a second aspect, a method and system for receiving an externally generated object comprises determining that the externally generated object is represented as an object class in one of a base table and a derived table.