Foreign workers could apply for an exemption certificate (Befreiungsschein) if they had already lived in Germany for an uninterrupted period of more than ten years. They then no longer needed to apply for a work permit every two years. This never applied to civilian forced laborers who came to the German Reich after the German army invaded Poland on September 1, 1939. However, the inscription shows that the work permit document dates back to regulations for foreign workers from 1933.