Overlapping above-base marks in Balinese

[dscorbett]

Font

NotoSerifBalinese-Regular.ttf

Where the font came from, and when

Site: https://github.com/googlefonts/noto-fonts/blob/af306de71ce51b9ce75389b163026427953606cf/phaseIII_only/unhinted/ttf/NotoSerifBalinese/NotoSerifBalinese-Regular.ttf
Date: 2019-04-25

Font version

Version 2.000

Issue

Many combinations of Balinese above-base marks overlap each other.

Character data

ᬕ᬴ᬷᬰᬶᬁ
U+1B15 BALINESE LETTER GA
U+1B34 BALINESE SIGN REREKAN
U+1B37 BALINESE VOWEL SIGN ULU SARI
U+1B30 BALINESE LETTER SA SAGA
U+1B36 BALINESE VOWEL SIGN ULU
U+1B01 BALINESE SIGN ULU CANDRA

Screenshot

[kamholz]

The correct rendering of above-base marks depends on the particular marks. For example, rerekan goes left of ulu sari and ulu goes below candra. Different codepoint orders of these marks would either produce the same result or simply be wrong (but I'm not sure if there is a prescriptive order). Many other combinations are possible.

This screenshot shows correct rendering of the above-referenced two combinations in Vimala, a font by Aditya Bayu Perdana:

[NorbertLindenberg]

The Universal Shaping Engine documentation specifies the order in which it expects the characters within a syllable:
https://docs.microsoft.com/en-us/typography/script-development/use#clustervalidation

Balinese fonts that aren’t based on the USE may assume a different order, or may not enforce any particular order.