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.
You can also use corn startch (aka 'corn flour' in europe) to make a lighter textured short bread-sub 1/4 corn startch for regular flour used. You might also try using straight Maseca (mexican corn meal) to make the short bread, it comes out very sweet and tender.