Ever since T146675 was implemented on the Norwegian Bokmål Wikipedia, there have been some issues because of the way articles/sortkeys starting with numbers are lumped together under the heading "0–9". In normal article categories I don't see a problem with it, but in maintenance categories and especially Babel categories, it breaks things to the point that they are not useful.
Some examples:
- This category sorts articles based on what year the {{best before}} template indicates (using last digit of the year), but everything is lumped together, so the sorting in the category doesn't make any sense.
- Most importartly: Babel categories, which sort users by their level of knowledge of a language. 1 is basic, 2 is intermediate, 3 is advanced, etc. See e.g. this category, but really any babel category will do.
I'm not sure how to solve this, short of a solution like what's outlined in T30397.