Given the elements of a corpus at a particular level, we state what limitations there are on the random distribution (within utterances of the corpus) of each element relative to each other element at that level. For phonemic elements, the limitations are stated over a short range of a few elements before and after it and those simultaneous with it; for morphemic elements, the limitations are stated over the whole utterance or […] over any given part of it.
- Harris (1951), Pag. 364