Pakpak • Simalungun • Toba • Mandailing
This diacritic can only be found in Karo and Simalungun. In Simalungun it is called Hatulungan, and in Karo Ketolongen. The root words are hence tulung and tolong.
The phonetical value in Karo is [o], but in Simalungun it is [ou].
Simalungun is the only Batak language that has an own diacritic for /ou/ even though the diphthong [ou] is present in both Simalungun and in Karo.
In Karo, the diphthong [ou] is only present in Karo Jahe – the piedmont zone of the regencies of Deli-Serdang and Langkat, but not in the highlands, also known as Karo Gugung or the Karo regency.
Karo also knows a second form of the Ketolongen, which has precisely the same shape as Pakpak [ǝ], namely ᯆᯨ, but is used in Karo for [o].