Why do the Hebrew Alphabetic Presentation Forms Exist

[Richard Wordingham]

On Thu, 4 Jun 2020 03:26:30 +0000 (UTC)
abrahamgross--- via Unicode <unicode at unicode.org> wrote:

> Why do the final forms of the hebrew letters (םןץףך) exist as
> separate codepoints from their regular counterparts (מנצפכ), when
> arabic - which has up to 4 forms for each letter - only got a single
> codepoint per letter?

TUS gives an explanation for the separate encoding of those final
forms, in the section on Hebrew.  Devising rules for automatic selection
would be too difficult, and would probably need an override mechanism
anyway.  There are similar cases scattered through Unicode.  Off the
top of my head I can think of:

U+017F LATIN SMALL LETTER LONG S

U+03C2 GREEK SMALL LETTER FINAL SIGMA

U+1A55 TAI THAM CONSONANT SIGN MEDIAL RA

U+1A56 TAI THAM CONSONANT SIGN MEDIAL LA

Richard.