The Kawi script descended from the Grantha script around the 8th century BC and was used across the islands of Borneo, Java, Bali, and Sumatra. The script originated in Java, and as a result is also sometimes called Old Javanese.
Kawi was an abugida; consonant characters are read with an inherent vowel. Diacritics are added to the consonant either to suppress the vowel entirely or to change it to a different vowel.
The Kawi alphabet developed around the 16th century AD into the current Javanese script. This transition was more stylistic than structural; the visual composition of the script changed but the way it worked stayed the same.
This script is not currently recognized by the ISO 15924 standard, but is included in ScriptSource for research purposes. If you have any information on this script, please add the information to this site. Your contributions can be a great help in refining and expanding the ISO 15924 standard. The Script Encoding Initiative is working to support the inclusion of this script in the standard, and contributions here will support their efforts.