Khmer script
Khmer has 35 consonants, but 2 of them are not used anymore. There are two categories of consonants: A-series and O-series. The A-series consonants end with an -aw sound (/ɑː/ in IPA) but the O-series consonants end with an -oh sound (/ɔː/ in IPA). For instance, ក (/kɑː/, "neck") is pronounced kaw and គ (/kɔː/, "mute") is pronounced koh. Both of them have the "k" sound but they end in different sounds because ក is A-series while គ is O-series.