Deprecated Characters
Some Arabic group of letters, Arabic Presentation
Forms-B (FB50-FDFF) or Arabic Presentation
Forms-A (FE70-FEFC), have a proper code point as group of
letters. This is proposed for Arabic diacritics, contextual forms
of letters, ligatures or letter variants needed for some
languages. For example diacritic in VEH ﭪ
(U+FB6A), contextual AIN ﻌ (U+FECC), ligatures ﳌ
(U+FCCC) or ﶊ (U+FD8A)
etc...
The presentation forms are present only for compatibility with
older standards, and are not currently needed for coding text.
They are now deprecated by Unicode (reference needed).
Some needs for these forms
However, some author might wish to use these forms for cases
where such as:
- Force joining
letter in some old tools where joining doesn't occur, or
when rendering tools don't join letters marked-up separately
(e.g. as colored letters).
vs. 
- Stylistic need,
when some font doesn't render some optional ligatures, or need
for some calligraphic letters (...).
vs. 
where
Meem+Heh+Meem ligature (U+FD8A
) is used.
- Mandatory ligatures
may not be done by some typefaces (marked Lamalef is
written Lam and Alef in 'Traditonal Arabic'
and may be other fonts).
vs. 
- etc. @@
Some pro and cons for Presentation Forms
Pro
- Color different letters/parts of a word.
- Show isolated letters for some purpose (logical
memory )
-
- e.g. "...In memory, W3C
المغرب is stored W3C ا ﻟ ﻣ ﻐ ﺮ ب in
typing order..."
- for some pedagogical reason, show separate ligature
letters.
- Force ligatures for aesthetic or some reason, when fonts
doesn't permit
-
- example:
Lam+Meem have same color, when each
letter (or glyph) has different color. Compare with
- Force mandatory ligature not done because of marks, case 3
above
- Use a tool which doesn't join letters, case 1
above
- @@...
Cons
- Presentation Forms-A codes almost ligatures. However,
ligature is not a char but a writing style for joining letters.
So it can be applied to almost any group of letters.
- Cannot encode all ligatures
- Cannot compare strings with ligatures, unless a known and
standard way to compose/decompose all ligatures
- @@...