At the slight risk of seeming to self-promote... Following on from Sue
Renaud's and Cathy Spude's comments on functional categories, might I also
recommend my own paper on the use of functional categories in Australian
historical archaeology as relevant to the points they were making:

Brooks, A.
2005  Observing Formalities - the Use of Functional Artefact [sic]
Categories in Australian Historical Archaeology. _Australasian Historical
Archaeology_ 23:7-14

While written for an Australian audiences, it does address broader issues
of polyfunctionality and terminology that would be germane to a Northern
Hemisphere discussion of these issues.

Alasdair Brooks