Several years ago, Russ started his own heating and cooling business. As his business grew, Russ noticed that his traditional structure was becoming difficult to coordinate, making communication difficult and decision making slow. He decided to restructure his business, organizing his departments into six larger groups: (1) heating repairs, (2) heating sales, (3) heating installation, (4) air conditioning repairs, (5) air conditioning sales, and (6) air conditioning installation. What type of structure has Russ adopted?