Khmer sign coeng

Type the base consonant, coeng, then the next consonant.

On a Unicode Khmer keyboard, use the ordinary consonant key after the coeng marker; you do not need a separate subscript letter. For Khmer consonant stacking, repeat coeng before another subscript consonant. In ordinary modern spellings, enter vowel signs afterward, even when they display before or around the consonants.

What does Khmer coeng do?

It joins consonants into a written group.

Khmer consonant letters have a built-in vowel sound, called an inherent vowel. Coeng lets another consonant join the base without adding its own inherent vowel. The first consonant keeps its full form; the following one takes its subscript form.

Older spellings can use subscripts differently

A written group need not match one spoken syllable: modern Khmer can join consonants across a syllable boundary. In Middle Khmer, an earlier stage of the language, a subscript after a vowel could also represent a final consonant.

Khmer writing developed from southern Indian script traditions. An Old Khmer inscription at Angkor Borei dates to 611 CE and uses Early Pallava, a southern Indian script. Coeng’s digital stacking instruction represents a writing practice older than computers.