[...] product-oriented schemas have no counterpart in generative theory. They are generalisations over sets of complex or "derived" forms, such as "strung, stung, flung, hung", etc., which show what features these derived forms have but without stipulating the operations it takes to produce such forms.
- Bybee (2004), a pag.46

Product-oriented schemas are generalisations over non-basic forms rather than generalisations about the relation of a non-basic form to some underlying stem or base form. The product-oriented schema specifies only the phonological shape of the member of the category, but not does specify how that shape is to be achieved.
- Bybee (2004), a pag.58