OPS.8.1:4.4 - Compare signals and their return treatment
Compare the existing rule with a material alternative on the same arrivals, resources, receiving result and waiting origin. Keep the rule’s actual mechanism visible.
| Candidate rule | What permits new work | What to resolve about returns |
|---|---|---|
| Completion at a selected constrained activity triggers replenishment | That activity consumes the next ready supply and calls for its replacement. | Which later work can revisit this resource or occupy another resource needed for delivery? What ready supply and remaining capacity protect those visits? |
| A job’s departure frees a place in a limited loop | The controlled population falls below its limit. | Is a return inside that loop, or admitted through another rule after departure? Retain its load wherever it will be served. |
| Remaining workload fits the selected norms | The candidate’s contributions fit the resource-specific load rule. | Include repeated visits under that rule, distinguish known work from uncertain returns, and define what happens when feedback changes the load. |
| Acceptance permits the next start | The selected receiving event closes the exposure being protected. | Does waiting for this event preserve useful capacity, or unnecessarily hold a place while acceptance uses another resource? |
The names Drum-Buffer-Rope, CONWIP and workload control locate families of these methods; they do not settle the particular boundaries or exception rules. A rule can combine a replenishment signal with a return allowance or use a separate return queue. Evaluate that combination rather than assuming that choosing a name determines its behavior.
Compare the delay imposed on new work with the protected earlier result. If holding one job would starve an important resource, consider another ready job with compatible resource use, a smaller independently useful unit, another capable resource or a different start window. Any exception that spends protected capacity changes what the rule can support. OPS.7 and OPS.13 supply priority and commitment decisions when the two services cannot both be retained.