Abstract: A method for changing test substrates in a continuous-flow vacuum system in a multiple-treatment-step process cycle for treating a substrate, a treatment method using the method for changing test substrates, and systems for treating a plurality of substrates (61) and for changing test substrates. For at least two treatment steps, at least two test substrates (66) are transferred to a vacuum treatment system at the beginning of the process cycle and are transferred back out once the process cycle is concluded. Subsequently, the first test substrate (66) concurrently treated in this step is removed from the measurement position (70) it occupied during the treatment and is deposited in an empty position (71) without a test substrate (66). Subsequently, the second test substrate (66) which has not been treated yet is deposited in the resulting free measurement position (70) for the purpose of supplying the second test substrate to the subsequent treatment step.