U+1885 / U+1886 changed from Letter to Mark

I had said earlier that the two Baludas (U+1885/1886) would probably be better processed as marks rather than letters.
I find the following differences between the two Baludas and the one unquestionable mark in the Mongolian block - U+18A9 Dagalga ...



U+18A9

U+1885/1886

CATEGORY

Mark, Nonspacing (MN)

Letter, Other

COMBINE

228

0

BIDI

Non-Spacing Mark

Left-to-Right

Character.getDirectionality()

Directionality_Nonspacing_Mark[8]

Left_to_Right 0

Character.getType()

6

5

Character.isJavaIdentifierStart()

No

Yes

Character.isLetter()

No

Yes

Character.isLetterOrDigit()

No

Yes

Character.isUnicodeIdentifierStart()

No

Yes


Given that the Baluda stations itself to the right of an existent vertical letter in similar fashion to the Dagalga stationing itself on the left side of the given vertical letter, I would say that we recommend redefining the features associated with the two Baludas to match the Dagalga. Then test it to verify that shaping behavior is as expected.

If we made the above changes to the feature set of the U+1885/1886 would this allow us to shape the Baludas like we do the Dagalga?

ArabicShaping.txt does not seem to make any distinction between the mark U+18A9 and the two Baludas.

Greg