ISO 15919 Relation to other systems Comparison with UNRSGN and IAST

| Devanagari | ISO_15919 | UNRSGN | IAST | Comment_ |
|---|---|---|---|---|
| ए /  े | ē | e | e | To distinguish between long and short `e` in Dravidian languages, `e` now represents ऎ /  ॆ (short). Note that the use of ē is considered optional in ISO 15919, and using e for ए (long) is acceptable for languages that do not distinguish long and short e. |
| ओ /  ो | ō | o | o | To distinguish between long and short `o` in Dravidian languages, `o` now represents ऒ /  ॊ (short). Note that the use of ō is considered optional in ISO 15919, and using o for ओ (long) is acceptable for languages that do not distinguish long and short o. |