German certificate of employment Arbeitszeugnis is a carefully coded document to be studied with a list of words and expressions.
Knowing the German language fully is not only knowing the words and grammar. Because hints play a huge role in German. They never speak their mind directly. A direct statement is often perceived as aggression, or a threat, or arrogance. This is not surprising, because if, as you will see later, a negative characteristic is hidden under the indication of punctuality, then the mind, looking for subtext everywhere, will see an insult in simple direct criticism.