Unicode Arabic Mark Rendering UTR #53 Now Published

[arno.schmitt via Unicode]

The paper adopted treats the word shown (fa-ʾulāʾika) writing
with an unkown letter +  kasra below + hamza below.
I thought, in Unicode I should use 'ARABIC LETTER YEH WITH HAMZA ABOVE' 
(U+0626) or its phonological equivilant 'ARABIC LETTER YEH WITH HAMZA 
BELOW' (U+0826) or the basic letter 'ARABIC LETTER YEH WITH HAMZA' 
(U+0825). My error or an inconsistency in Unicode?

Am 09.10.2018 um 21:32 schrieb announcements at unicode.org:
> exampleThe combining classes of Arabic combining characters in Unicode 
> are different than combining classes in most other scripts. They are a 
> mixture of special classes for specific marks plus two more generalized 
> classes for all the other marks. This has resulted in inconsistent 
> and/or incorrect rendering for sequences with multiple combining marks 
> since Unicode 2.0.
> 
> 
> The Arabic Mark Transient Reordering Algorithm (AMTRA) described in UTR 
> #53 <http://www.unicode.org/reports/tr53/> is the recommended solution 
> to achieving correct and consistent rendering of Arabic combining mark 
> sequences. This algorithm provides results that match user expectations 
> and assures that canonically equivalent sequences are rendered 
> identically, independent of the order of the combining marks.
> 
> 
> The concepts in this algorithm were first proposed four years ago by 
> Roozbeh Pournader. We are pleased it has now been published as an 
> official Technical Report.
>