A special case of environments which can only be recognized in terms of morphemes is the environment of the morphemic segments whose phonemes are repeated in the utterance (agreement morphemes). In 12.323 it was seen that in utterances like Moroccan Arabic 'lbit lkbir' ‘the large room’, 'luld lkbir' ‘the big child’, we have a morphemic segment 'l … l …' ‘the’. In 'lbit lkbir luuƏl' ‘the first large room’ we similarly have a morphemic segment 'l … l … l …' ‘the’, and in 'lbit' ‘the room’ we have 'l' ‘the’. These three are complementary: the number of occurrences of 'l' depends on the number of morphemes. But the 'l' does not occur before every morpheme: we have 'lbit lkbir dial buia' ‘the large room of my father’. We therefore group all the complementary 'l' sequences into one morpheme {'l'} ‘the’, and say that this morpheme occurs over a particular exactly-stated domain (namely, sequences of stated morphemes including 'kbir', 'bit', but not including 'dial'): portions of the {'l'} morpheme occur, if at all, before every morpheme of this particular domain. When the morpheme {'l'} occurs, we have /l/ before every morpheme which is included in the domain.
- Harris (1951), Pag. 210