1. A method for operating a controllable multi-variable process, wherein a multi-dimensional display representation of the variables according to individual coordinate axes is derived, sets of values of process- and quality-variables accumulated respectively from previous multiple operations of the process are stored, and current values of the process- and quality-variables are indicated on their respective axes in relation selectively to one or other of a plurality of operational envelopes which are each derived from at least some of the accumulated sets of values and which define bounds for the variables and differ from one another in the bounds defined for at least one of the variables, the particular one of the envelopes in relation to which the current values are indicated being dependent on the current value of at least one of the process-variables.