| 700 / | HD | DATA PROCESSING: GENERIC CONTROL SYSTEMS OR SPECIFIC APPLICATIONS |
| 90 | DD | SPECIFIC APPLICATION, APPARATUS OR PROCESS {16} |
| 266 | | .~ Chemical process control or monitoring system {6} |
| 267 | DD | .~.~> Titration or pH level |
| 268 | DD | .~.~> Synthesis process {1} |
| 270 | DD | .~.~> Distillation |
| 271 | DD | .~.~> Refinement or purification or rejuvenation {1} |
| 273 | DD | .~.~> Separation process |
| 274 | DD | .~.~> Control of combustion or heating apparatus (e.g., kiln, furnace, autoclave, burner, combustion system) |