| 700 / | HD | DATA PROCESSING: GENERIC CONTROL SYSTEMS OR SPECIFIC APPLICATIONS |
| 90 | DD | SPECIFIC APPLICATION, APPARATUS OR PROCESS {16} |
| 275 | DD | .~ Mechanical control system {5} |
| 276 | | .~.~ HVAC control {2} |
| 277 | DD | .~.~.~> Multiple zones |
| 278 | DD | .~.~.~> Specific thermally responsive controller |