typography - What are the origins of the commercial minus sign (⁒)?

While reading the Wikipedia article about the Plus and minus signs I found the so called commercial minus sign (Unicode character U+2052 and HTML symbol ⁒). It looks similar to an Obelus (÷) or Percent sign (%) as you can see:

After some more research and googling for the German term "kaufmännisches Minuszeichen" I found that the commercial minus sign was and is widely used in bookkeeping to indicate a minus sign such as the following example shows. (It was also common to write ./. on typewriters instead.)

100€ "deducting" 20% equals 80€

The problem is that I can’t find any good information about this symbol and its history. As @El Otmani Ali pointed out in his post one theory is that this symbol is a "quicker / cursive based variant of the division sign in some old German books" (see his answer and this mailing list on unicode.org). On the other hand why should we use a different symbol, when we want to set a character italic?

So, do you know the origins of this rarely used and not really documented sign?

^{Note: The sans-serif typeface DejaVu Sans was used in the examples.}

Answer

Based on an answer in this thread, this minus sign was used in bookkeeping, because the - was already in use.

After all the amounts were put in, they were checked twice. When the amount was correct, one would mark it by putting a little horizontal bar behind it. The bar meant the amount was correct.

Since the usual minus sign could be confusing and leading someone to believe an amount was checked when it wasn't, a different minus sign was used, the Commercial minus sign

Here is an example:

    100,00 -
+   100,00 -
./. 100,00 -
----------
    100,00 -