Currently, it is almost impossible to encode Quranic text correctly using unicode, which ended up with every one using his own, non-standard encoding to encode Quran. Here we summarize missed Unicode code points that are needed for Quran, with possible solutions.
In Cairo 1924 Mushaf and its decendants, Sequential Tanween is used to indicate Idghaam of the Tanween, thus making distnict characters, not stylistic variants.
Tanween with Small Meem
In Cairo 1924 Mushaf and its decendants, the second mark in Tanween is replaced by a small Meem to indicate Iqlaab (convertion) of Tanween into Meem, thus making a new distnict character.
In Quranic Rasm, chairless Hamza is a non-disjoining character. This means, when it comes in between two joinable characters, it doesn't separate them. An example for the behavior of Quranic Hamza, is the word /a'aadam/ in Q2:31, 33, 34.
Small letters in Quran can be divided into two categories. Some are diacritical, corrective small letters that are placed over base glyph. While others indicate missing letters and thus are placed in between base glyphs. Not all small Quranic letters are currently represented in Unicode.
Alef has the two types, but only diacritical one is currently encoded. We propose a new small Alef, that is placed in between base glyphs and has exactly the same behavior as the chairless Hamza proposed above.
Although, there is small spacing Waw in Unicode, there is a missing small non-spacing Waw in the word /li yasuu'uw/ (Q17:7). This Waw is similar to U+06E8 superscript noon and occur once in the Mushaf.
The corrective small seen in the word /yabsuTu/ (Q2:245), this is different from superscript cantillation mark (السكتة), U+06DC.