Den 18 maj 2017 10:13 fm skrev "Otared Kavian" <otared@gmail.com>:
Hi Hans,

Thanks for your explanations.
When using constructions such as $f’’_2(x)$, I will adapt my input  in order to get what seems correct.

Best regards: OK

> On 17 May 2017, at 17:17, Hans Hagen <pragma@wxs.nl> wrote:
>
> On 5/17/2017 8:35 AM, Otared Kavian wrote:
>> Hi Hans,
>>
>> Thanks for having fixed the behavior of the prime in the latest beta release (ConTeXt  version 2017.05.15 21:48).
>> However, as you may see in the two attached PDF files, the result is still incorrect when one types for example $f_2’’(x)$, which should give the same result as $f’’_2(x)$.
>> The correct behaviour is that obtained with mkii. Indeed one can circumvent the behaviour of the latest beta release of mkiv by using tricks such as the ones in the example code below, but this should be avoided in my opinion.
>
> well, it depends on how one sees this '' mess
>
> the problem with primes is that in macro packages they are messy entities that should collapse or not (active char mess) and the more clever a macro packages becomes the harder it becomes to makes it robust and/or to fight against such heuristics
>
> add to that the fact that the symbol itself is a funny positioned something already raised in a font or not i.e. sometimes in need of superscript and sometimes explicitly not
>
> for unicode we need to turn two '' into a double and ''' into a and triple such
>
> that said, in context these thingies are at some point intercepted and their current state is looked at: superscript? multipel in a row? one ebing the nucleus of another ... etc .. the current (working again) behavior is what we support and i don't look forward to more heuristics
>
>
>> The following PDF have been obtained with mkii and mkiv with the following example code.
>> Best regards: OK
>>
>> %%% begin derivatives-prime.tex
>> \starttext
>>
>> \startformula
>> f''_{2}(x) = f_{2}''(x) = f^{''}_{2}(x) = f_{2}^{''}(x) % = f^{{}^{''}}_{2}(x)
>> \stopformula
>> As one may see the result of \type{f_{2}''(x) = } $f_{2}''(x)$ is not correct in \type{mkiv}.
>>
>> The following positions of the superscripts \type{(3)} are correct both in \type{mkii} and in \type{mkiv}.
>> \startformula
>> f^{(3)}_{2}(x) = f_{2}^{(3)}(x)
>> \stopformula
>>
>> \stoptext
>> %%% end derivatives-prime.tex
>>
>>
>>
>> ___________________________________________________________________________________
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>>
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>> ___________________________________________________________________________________
>>
>
>
> --
>
> -----------------------------------------------------------------
>                                          Hans Hagen | PRAGMA ADE
>              Ridderstraat 27 | 8061 GH Hasselt | The Netherlands
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> -----------------------------------------------------------------
> ___________________________________________________________________________________
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>
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> ___________________________________________________________________________________

___________________________________________________________________________________
If your question is of interest to others as well, please add an entry to the Wiki!

maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context
webpage  : http://www.pragma-ade.nl / http://context.aanhet.net
archive  : https://bitbucket.org/phg/context-mirror/commits/
wiki     : http://contextgarden.net
___________________________________________________________________________________

OK, very good, it seems that we have a working solution and one specific way to write it. I have absolutely nothing against that, but I would like us (me?) to document it, since I think future users might have use of it. Is the math page in the wiki the right place? 

(It will take some time before I will be able to act. I'm currently travelling with close to no working connection.)

/Mikael