The following rules describe the nondistinctive functioning of sharping (palatalization). [...] Rule P 6a. Before the glide {j}, paired morphonemes are normally sharped. [...] Rule P 6b. Before acute compact (i.e. palatal) consonants which are (non-distinctively) sharped, acute consonants are sharped. [...] Rule P 6c. Before plain acute noncompact (dental) consonants and before plain liquids, {*r} and noncompact (labial and dental) consonants are plain. [...] Rule P6d. Before {*i} and {*e}, compact grave (velar) consonants, which up to this point have remained unspecified with respect to sharping, become sharped.
- Halle (2004), a pag.31-32