This is the 1985th most frequent German word.
geprüft
Tested; checked; certified.
Here, 'geprüft' is used as the past participle of the verb 'prüfen', indicating that the action of examining or checking the document has been completed.
Das Dokument wurde gründlich geprüft.
The document was thoroughly examined.
In this instance, 'geprüft' is used as an adjective derived from the past participle of 'prüfen', describing someone who has undergone testing or certification.
Er ist ein geprüfter Techniker.
He is a certified technician.
This usage depicts 'geprüft' as part of the passive voice construction, where the regular inspection of the machines is indicated as an ongoing action.