Generating ordinal data
Ordinal data deals with categories, which themselves are ordered by meaning somehow, but we cannot strictly talk about the distance between the categories. In the example below, you can see that the ordinal data runs from awesome to terrible, with 5 categories explaining an entire ordinal range:



Having a look at the paper, it seems the define a uniform distribution $U(a, b)$ (probably continuous), which they then divide into some random categories, let's say 5, to follow the table above. So if we set the bound of the distribution, $a = 0$ and $b = 1$, we might randomly create five categories, such as:

Category :  a      b
----------------------
Awesome  : 0.00 - 0.09
Great    : 0.10 - 0.44
OK       : 0.45 - 0.46
Bad      : 0.47 - 0.59
Terrible : 0.60 - 1.00


We can see that they are ordinal, because they numerical values do signify some kind of meaningful order, but the size of the categories is not necessarily uniform. The authors generated them randomly.