After the discovery of Hittite and the development of the laryngeal theory, almost every instance of previous could be reduced to the vowel preceded or followed by the laryngeal (rendering the previously reconstructed short and long respectively). Against the possibility of PIE phoneme still today held by some Indo-Europeanists, the following can be said: vowel does not participate in ablaut alternations (it does not alternate with other vowels, as the "real" PIE vowels do), it makes no appearance in suffixes and endings, it appears in a very confined set of positions (usually after initial which could be the result of that phoneme being a-coloring, particularly likely if it was uvular ), and the reflexes of words upon which is reconstructed are usually confined only to a few Indo-European languages. For example, 'beard,' is confined to the western and northern daughter families. That makes it possible to ascribe it to some late PIE dialectalism or of expressive character (like the interjection 'alas') and so is not suitable for comparative analysis, or they are argued to have been borrowed from some other language which had phonemic (like Proto-Semitic > PIE ('aurochs')).