A German ligature that originally stood for 'sz', but can be transliterated as 'ss'. It is never found in Swiss German. It looks like a B, but sounds like an S. Compare to the boring language known as English, which only has the ligatures Ã and Å, which are rarely used.
The only other flour used in traditional pumpernickel is wheat flour, which is used as an ingredient in the sourdough starter, a pre-fermented flour, water and yeast mixture that combines with the rye flour to hold the bread together.
All-purpose flour is typically made from either hard red winter wheat, soft red winter wheat, or a combination of the two. Of the flours we used in the taste tests, five were made from hard winter wheat, one was made of soft wheat, and three were a mix of soft and hard.