 Thus it is useful to discuss the two in the same section.There are three modalities in Merei, realis (R), presupposition (PSP), and irrealis (IRR) (p. 28).All non-third person forms of negative modality markers share the same form "tei".The third person singular and dual negative forms can be formed by adding "tei" to the end of the positive form, whereas in the plural "tei" is added to the suffix -"ta" (p. 29).