It is used in high end CAD systems where tolerances need to be exact, there was also a wonderful decimal package for COBOL which was doing financial computations. Unknown to many (most?) people some early IBM Mainframes [1] were decimal machines.
If you work in 3D modeling you will be familiar with the effects of binary floating point as 'gaps' between polygons where they shouldn't be. Sometimes those gaps only appear at a certain scale because that is where the rounding gets it wrong, or if you compensate by always rounding up you get overlaps or texture issues.
http://speleotrove.com/decimal/
Any idea what decimal floating point is used for?
(I have little to no idea about CAD or financial software.
I can see that fixed-point decimal with two decimal places is useful for things where you want to be able to reason about rounding of cents.
I can also see that you'd want more than two decimal places for a lot of calculations, for instance computing interest.
But decimal floating point...what's specified in such a way that you need to use decimal floating point?
I checked the wikipedia decimal floating point page. Didn't see any concrete examples there either.)