What's the source where I can find a complete list of all currently valid and deprecated comma rules for the German language?
I do review a lot of documents at work and see tons of comma mistakes.
I'd like to have an authoritative source which I can point to and say: "Look,
- this sentence has a mistake here (the mistake),
- it requires a comma there (the correction),
- this is the comma rules that applies (rule from an authoritative source)
- and here is an example to illustrate it (example)."
My findings so far
Then, I looked at Duden which used to be considered to be the authoritative source for German language questions (don't know whether it stil is). I prefer the Duden to the Wikipedia article because every rule has a number which one can point to. For example:
Regel 104: Wenn der Beisatz Teil des Namens ist, steht kein Komma.
What I am still missing is a list of deprecated rules. For example, there used to be a rule that there is a comma before "und", if the subject of the second sentence is different from the one of the first sentence. The new rule is that the comma is optional.
Bislang galt es, vor den Konjunktionen und bzw. oder ein Komma zu setzen, wenn es sich um zwei gleichberechtigte Hauptsätze handelt. Diese Regel ist zwar nicht allzu schwierig, aber zeitraubend. Denn meistens musste man den Satz zweimal lesen, um die Hauptsätze überhaupt zu erkennen. Mit der neuen Reform entfällt dies. Source: Akademie.de.
Finally, there are numerous other collections of the German comma rules, such as the one on Akademie.de, but I wouldn't consider them to be authoritative. It's hard for me to evaluate the correctness of those sources.