Ok...found this piece of info on the site
123Recht, which is a good place to go if you have individual/specific questions. You pay a small fee (€10-15) and get your questions answered by a lawyer with knowledge in that area. One piece said:
QUOTE
2. Sollte vertraglich nichts anderes geregelt sein, dann haben Sie pro Monat einen Anspruch auf zwei Urlaubstage.
If your contract doesn't say anything else, you are entitled to 2 vacation days per month. (rough translation)
That means 12x2 = 24, so 24 days are legally required. However, many people have 30 days of vacation in their contracts. I don't know why. I even know someone who has 33 days.