below. Phonology Tone As analyzed by Sapir, Jabo was represented as possessing four phonemically distinct pitch levels (or registers), independent of phonation type or supraglottal articulation. Furthermore, mono-moraic (short syllable) glides from any register to any other register were phonotactically possible. This meant that there could possibly be sixteen distinct, segmentally-identical short monosyllables with significative pitch contours—more if long syllables were admitted. The not-uncommon word types (CVV) and CVCV could potentially have 256 possible prosodic contours, each with a different dictionary meaning for the same three or four segments. Sapir devised a system of "tone letters" for specifying tone, but they are inconvenient to typeset and not included in the Unicode inventory. The common convention for Kru languages is to mark tone with subscript or superscript tone numbers following the vowel, with 1 denoting the highest register. They may also be transcribed in the IPA with tone letters or diacritics. The default tone of the language, in Jabo tone 2, is generally left unmarked in a diacritic system. As an example, take the word "Jabo people", which is tone 2. For literacy purposes some system of diacritics would likely be preferable. Falling contour tones (parentheses) are very rare. Where they occur, they seem to be in imitation of other languages or dialects. Vowels The vowels marked with a subscript dot are said to be "dark" or "turbid". This is usually understood as being due to an articulation with pharyngeal constriction. Advanced tongue root position or faucalization may also be involved. This last possibility may make it simpler to rationalize the apparent markedness of the extreme vowels and , which are said always to be "turbid". Nasalized versions of , and were reported, but it is doubtful whether they have phonemic status. Since the articulations involved are probably to a degree mutually exclusive (velic and pharyngeal), and since they seem to contribute similar auditory components (nasalization and "turbidity"), they are more likely to be allophones resulting from assimilation. Sapir was an excellent phonetician, so his transcriptions may be narrowly accurate, whatever their phonological implication. In the case of Herzog or Blooah, one suspects that there may have been a normalization attempt by the transcriber. This nonetheless gives an appearance of vowel harmony to Jabo phonology. Syllabic nasals and also occur. Related to this is a phenomenon of prenasalization, termed "anacrusis" by Sapir by analogy with the metrical term. It is probably