(under subclass 255) Subject matter including significantly claimed details of frequency control means (as defined in subclass 255) combined with other control means (e.g., tone control, selectivity control) or other broadly included control means which may be included by the name only (e.g., volume control).
(1) Note. To complete the field of search for subject matter found in further search must be made in subclasses, or classes, relating to other control means. For example, if the other control means comprises selectivity control the further search should be in subclass 266, etc.
