I can not recognize the (new?) icons for "printable" "unused" and "approval" (maybe still under construction?) Maybe letters would do? M for metadata looks good. Draft icon is "readable" as well. (My browser: firefox/windows). I understand that that's a minor issue.
There is a probalem in the CZ cache, even though I uploaded new designed the old design is still shown, although cramped into the tiny 17x17 px space. I thought it might sort itself out last night but its still corrupt. I just uploaded the new design into a new image. I also played with the idea of just using letters. See below for two possible options.

We can proceed from here. All colours, sizes and positions can be adjusted quite easily.
I do not understand why the Test Article has two contradictory categories: "Advanced" and "Approved". Minor fix?
I just changed this. If you're interested, the category placement is controlled by the following template (
Template:Checklist4). Changes to this one central template will change the categories on ALL articles using the subpages template. This will be really useful in the future are we need to adjust category names, add categories or remove categories. Literally every article can be changed with one edit.
Another minor remark - or just curiosity: are there advantages of putting the central place for categories in the Template namespace? I see no problem with it, but at the first sight, putting it on a subpage to the article (in the mainspace) would IMHO be more natural.
Originally I had tried to do this, however, when reading the information from the matadata page it turns out that it can only be read from the template namespace (I use the following format {{ARTICLENAME/Metadata|info=status}} and for an approved article this would return a value =0). Is there way to read information from the main space?
At some time we could rethink whether we need e.g. "Biology External" category at all -- only "Biology" and "External", and a tool to find the intersection. At present categories under the Test Article do not look very good as there are obvious redundancies. Consider e.g. that "approved" or "advanced" always implies "nonstub" and "internal". Also numerous "intersections" of "biology" category with nonstub/internal etc are implied by merely 2 "generators": "biology" and "approved".
Now, perhaps there is nothing to do about it and some of them are needed.
As far as I can tell, the great advantage of this system (the subpage template) is that once we decide to get rid of something, we can easily do it.
All your points are valid here and at the end
you hit the nail on the head. I think the original purpose for all these categories was for accounting purposes. For example, all the nice stats pages you made probably used the categories? At some point we need to consider what categories are appropraite for each article status, 0-4.
One more question: how to archive the talk page and make appear the links under the checklist?
The archive should live at Talk:ARTICLENAME/Archive 1 or Talk:ARTICLENAME/Archive 2 (Note the space between the Archive and the number!). If you create the archive page in that format the archive link will automatically appear in the checklist table on the talk page.
As far as the archive pages are concerned I have not modified the subpages template to function on them correctly (it can be done). So at present the old archive box should still be used. You can see that I did this for the Test article
Archive 1 and
Archive 2.