one key feature that khmer has, while thai and lao do not, is that consonant letters have subscript forms. subscript forms are forms of consonant letters that are written underneath other letters. similar to how different letters in the latin alphabet have capital or lowercase forms that look different from each other, consonants in khmer have standard and subscript forms. these are used to write consonant strings. for example, in the word khmer (ខ្មែរ), the "kh + m" consonant string is written as ខ្ម. by themselves, the consonants that make up the "kh + m" cluster would be written as ខ and ម, but since the "m" consonant is the second part of a consonant string, it is written differently under the first consonant in the cluster ខ. so ្ម is the subscript form of ម.