Representation of Malayalam /au/ Vowel in Traditional and Modern Orthography

Public Review Issue #93: Representation of Malayalam /au/ Vowel in Traditional and Modern Orthography

In traditional Malayalam orthography, the vowel sound /au/ is represented by a two-part vowel sign 0D4C . In modern ways of writing Malayalam (including the official reformed orthography) the vowel sound /au/ is represented by a single part vowel sign which looks like the right part alone: 0D57 .

Unicode encodes U+0D4C 0D4C MALAYALAM VOWEL SIGN AU and U+0D57 0D57 MALAYALAM AU LENGTH MARK. The latter was encoded with the intent that it represent a glyph for the right half of U+0D4C. This mark U+0D57 happens to correspond to the representation of the sound /au/ in the modern orthography.

The question for public input is which of the following two options should be recommended:

Option A: The modern orthography would use U+0D57 0D57 for /au/. Under this option, both orthographies can be represented in the same font, but the spelling of /au/ would change when switching between orthographies.

Option B: Text in the modern orthography would use U+0D4C for /au/. Any such text would require a distinct font to display a one-part sign 0D57 for the modern orthographic appearance. Thus the same spelling would be used for both orthographies, requiring a change in font to display text in one style or the other.

Points to be considered by reviewers:

In a script such as Malayalam there is a question about whether this kind of a change is actually a spelling change requiring an encoding difference, or is simply a change of shape of an existing character.
Ordinarily whenever spelling changes, text is represented by a different character sequence than it was before.
The choice of one of these options affects the ISCII mapping to the Unicode standard because U+0D4C is derived from, and is mapped to, the ISCII standard.
Under option A the sorting algorithm would have to be adjusted to sort the two characters for /au/ equivalently.
U+0D4C has a canonical decomposition to the sequence <U+0D46, U+0D57> which is stable in the Unicode Standard and can never be changed. Therefore the sequence <U+0D46, U+0D57> will remain equivalent to a single instance of U+0D4C independent of the option chosen.