thank you for your answer. Now I have another question : in your opinion, does it make sense to have articles like *h₂ows-, where a noun is ended by a "-" ? Wouldn't it be more logical to have this only for roots, and something like *ǵr̥h₂nóm for nouns (*h₂ows) ?
We don't use - only for roots, we also use it for verb stems. The - just means that we don't know what followed it or that several possible things may have followed it, but that the word is not complete without it.