Frequently, the phonemic features characteristic of a construction occur at the boundaries of its domain. Certain phoneme sequences may occur only or never if part of the sequence is the end of one construction while the rest is the beginning of the next. Thus in Hidatsa of North Dakota, 'kk' occurs across the boundary of two constructions, but never otherwise: 'ha'ruk ka'raּk' ‘then running’ (two constructions in that there are two loud stresses; the morphemes are 'he' ‘say, do’, 'ru' subject changer, 'ak' indicator of immediately preceding action), but 'aּˀah'kiּc' ‘he brought him to it’ (one construction with one loud stress; the morphemes are 'eּˀe' ‘have’, 'ak' indicator of immediately preceding action, with 'k' replaced regularly by 'h' before close juncture + 'k, kiּ' ‘get back’, 'c' indicator of action). From the presence of 'kk' we know not only that there are two constructions present, but also where their boundary lies.
- Harris (1951), Pag. 343