Customizable display type when showing grades
At the moment grades are displayed as 1/1000 (per mille) but other parts of the globe prefer percent or ratio.
It should be handled similarly to units (inch/feet/cm/..)
Now available in RailModeller Pro 5.3.7

Added for RailModeller Pro 5.3.7

Grade input/output will be configurable with the 3 most common notations supported initially:
 per mille (common in Central Europe)
 percent (common in the US)
 ratio (common in the UK) 
All to be added the same way Units can be customized via the app's preferences!

From Wikipedia:
There are several ways to express slope:
 as an angle of inclination to the horizontal. (This is the angle α opposite the "rise" side of a triangle with a right angle between vertical rise and horizontal run.)
 as a percentage. In the U.S., this percentage "grade" is the most commonly used unit for communicating slopes in transportation (streets, roads, highways and rail tracks), surveying, construction, and civil engineering.
 as a per mille figure. This is commonly used in Europe to denote the incline of a railway.
 as a ratio of one part rise to so many parts run. For example, a slope that has a rise of 5 feet for every 100 feet of run would have a slope ratio of 1 in 20. (The word "in" is normally used rather than the mathematical ratio notation of "1:20").
This is generally the method used to describe railway grades in Australia and the UK.