[...] lexical structure framework [...] predicts that a stem of any lexical category can be inserted into a word tree as a sister to a stem of any other lexical category to form a compound which will have the category and other property of the right-hand stem; since stems by definition have no subcategorization restrictions, all combinations could be attested. Moreover, since the framework as it stands places no restrictions on compound formation, it also predicts that all types of compounds should be equally productive.
- Lieber (2004), Pag. 212