OPS.10.1:4.1 - Define the completion question and its clock

Choose the operating population, arrival event, completion event and horizon. Keep an order, its visits and its accepted result distinct. For each alternative, measure customer waiting from the same event unless the question concerns that starting event.

State the output needed: all listed jobs finished by a date; a mean residence time in a continuing regime; a fraction completed within a duration; a probability under a specified model; or protection against a stated disturbance. Recover the initial unfinished work and its remaining requirements. A system started empty is a different input from a busy operation observed halfway through a shift.

For example, “the two jobs need four hours on average” does not yet answer “with what probability will both be complete by hour four?” Section 5.2 constructs both answers from the same service assumptions.