I describe N'Ko counter styles at https://r12a.github.io/scripts/nkoo/nqo.html#lists and show some examples.

The cardinal style is straightforward, but I'm not clear how to write a pattern for the ordinal style, and I wonder whether someone can help (@tabatkins), or whether it needs to be described in the spec, like Ethiopic, etc.

The issue has to do with combining marks that are attached only to the last digit (N'Ko digits run RTL, unlike Arabic). Different combining marks, in different locations relative to the base, are used if that digit is 1 vs anything else.