The final consonantal letter of the alphabet, "s2", has a disputed origin along with both "appended" glottals, but "The patent similarity of "form" between the Ugaritic symbol transliterated and the s-character of the later Northwest Semitic script makes a common origin likely, but the reason for the addition of this sign to the Ugaritic alphabet is unclear (compare Segert 1983:201-218; Dietrich and Loretz 1988). In "function", [s2 is like Ugaritic s, but only in certain words – other s-words are never written with "Ugaritic, in The Ancient Languages of Syria-Palestine and Arabia"</ref> The words that show "s2" are predominantly borrowings, and thus it is often thought to be a late addition to the alphabet representing a foreign sound that could be approximated by native /s/; Huehnergard and Pardee make it the affricate /ts/. Segert instead theorizes that it may have been syllabic /su/, and for this reason grouped with the other syllabic signs /ʔi/ and /ʔu/.