Classes: voiceless labiodental fricative
Implicit classes: obstruent consonant C
Features: -voice labial -sonorant +continuant +strident
Related rules
Origin
lat-velars: {ǵʰ|gʰ|gʷʰ} > g / n_, gʰ > f / _u, {ḱ|ǵ} > {k|g}, {ǵʰ|gʰ} > hlat-gwh: gʷʰ > f / #_, gʷʰ > u̯lat-voiced-aspirates: {bʰ|dʰ} > f / #_, bʰ > b, dʰ > b / {r|u}_, dʰ > b / _{r|u|u̯|l}, dʰ > d