[inkyoto]

> … in Thai, for example, the syllable NA is written นา with น and า treated as separate characters, while in Devanagari, NA is written ना where न is the N sound and the A sound ा is a spacing mark which changes the shape and spacing of the first letter to give ना.

Worth noting that «-a» is often implied and both, Thai and Devanagari (and in nearly all other Brahmi and Pali derived scripts), and is implicitely derived by the language speaker, and therefore is dropped from the spelling most of the time except for specific cases.

[innocenat]

-a sound (ะ) isn't dropped in Thai in most case. It's only dropped in specific cases, mostly from words with Pali/Sanskrit origin.