Listed in order from highest to lowest are the categories of the hierarchy that isare most commonly used in theoretical phonology. There is some disagreement on the arrangement and inclusion of units, especially those that reside higher in the hierarchy. For example, the clitic group is not considered to be a separate level in Selkirk's version of the hierarchy,<ref name="selkirk1996">{{cite journal | last = Selkirk | first = E. O. | title = The prosodic structure of function words | journal = International Conference on Bootstrapping from Speech to Grammar in Early Acquisition | editor-last = Martin | editor-first = J. | editor2-last = Demuth | editor2-first = K. | ___location = Hillsdale, NJ | publisher = Lawrence Erlbaum | date = 1996}}</ref> while the minor phrase or accentual phrase are not considered to be separate from the phonological phrase in Hayes'<ref name="hayes1989">{{cite journal | last = Hayes | first = Bruce | title = The prosodic hierarchy in meter | journal = Phonetics and Phonology Vol. 1: Rhythm and Meter | editor-last = Kiparsky | editor-first = P. | editor-last2 = Youmans | editor-first2 = G. | publisher = Academic Press | ___location = San Diego | pages = 201–260 | date = 1989}}</ref> and Nespor & Vogel's hierarchies.<ref name="nespor1986">{{cite book | last = Nespor | first = M. | author2 = Vogel | first2 = I. | title = Prosodic Phonology | publisher = Foris Publications | ___location = Dordrecht | date = 1986 }}</ref><ref name="shattuck1996">{{cite journal | last = Shattuck-Hufnagel | first = Stephanie | last2 = Turk | first2 = Alice | title = A Prosody Tutorial for Investigators of Auditory Sentence Processing | journal = Journal of Psycholinguistic Research | volume = 25 | issue = 2 | pages = 193–247 | date = 1996 }}</ref>
