Unicode: Redefining AU length marker U+0D57

Current meaning of the two AU signs are described below:

0D4C MALAYALAM VOWEL SIGN AU

• Two part symbol of AU is not used now-a-days.
• Could be represented by two part symbol in fonts supporting old orthography
• Could be represented by right part alone in fonts supporting new orthography

0D57 MALAYALAM VOWEL SIGN AU - RIGHT PART ALONE

• Should not be used as MALAYALAM VOWEL SIGN AU.
• Represents the right half of 0D4C irrespective of the orthography supported by the font.
• Only required when the right part alone need to be specifically mentioned. eg: in a grammar book.
• Common day-to-day texts need not use this symbol at all.
  

This assignment of meaning to these symbol causes lots of confusion. Also, it can potentially violate Uniqueness Rule when people interchangably use 0D4C and 0D57 to denote AU symbol in new orthography.

Following are the possible solutions for this:

1. Deprecate 0D57 and loose the facility to display right part alone in an old orthography font.
2. Make 0D57 something like a joiner which is typically transparent to automated tools like search engines. U+0D57 will have meaning only when it is followed by U+0D47 and that combination will suppress the left part ofU+0D47, irrespective of the font.