ABMAHNUNG
WARNING
The “warning” is a legal term from general employment law. The warning usually precedes termination without notice. Deficiencies in performance or behavioral reasons on the part of the employee can trigger a warning. The employer must draw the employee’s attention to the violation of his contractual obligations, together with the request to behave in accordance with the contract in the future. Cancellation is threatened in the event of recurrence. Not only the employer but also employees who are authorized to give binding instructions are entitled to issue a warning. The employer is entitled to place warnings in an employee’s personnel file.
This is something that does sometimes occur, especially if you're not aware of all your contractual obligations. For example, if you are double cast on a role and the other singer is scheduled to sing that night you are nevertheless required to be within a certain distance of the theater and reachable in case of late cancellation. You are also not permitted to go off to other jobs or rehearsals without asking permission from your theater. These violations could bring an Abmahnung, which is a very serious thing.