Yes, Adam, that works. Though it can be a laborious solution, since it 
means creating keys for everything in a sub entry list (and I have many 
instances, 40 or more in some cases). However, I did not ask for a 
'simple' solution, just a solution! Thank you.

Julian

On 1/2/22 11:09, Adam Reviczky wrote:
> Hi Julian,
>
> How about using the keys in every instance?
>
> \setupregister[index][n=1,method={zc,pc,zm,pm,uc},style=WORD]
> \defineprocessor[special][style=italic]
>
> \starttext
> P\index[Plenary+periti]{Plenary Council+{\it periti} (experts)}
> B\index[Plenary+beriti]{Plenary Council+{\it beriti} (experts)}
> A\index[Plenary+aeriti]{Plenary Council+aeriti (experts)}
>
> S\index[animals+special]{animals+‘special kinds’}
> B\index[animals+bpecial]{animals+bpecial}
> A\index[animals+apecial]{animals+‘apecial’}
> U\index[animals+upecial]{animals+‘upecial’}
> T\index[animals+tpecial]{animals+tpecial}
>
> \placeindex
> \stoptext
>
> See result in: https://live.contextgarden.net/cgi-bin/result.cgi?id=j46XhZ
>
> Adam
>
> On Mon, Jan 31, 2022 at 10:38 PM jbf via ntg-context 
> <ntg-context@ntg.nl> wrote:
>
>     Let me come back to the unresolved (for me) question of two
>     situations in sub entries to a book index (register). Sub entries
>     that have formatting or sub entries that are surrounded by quote
>     marks (straight or curly, it makes no difference) do not appear in
>     the correct alphabetical order.
>
>     Two attempts on my part:
>
>     text before \index[Plenary+periti]{Plenary Council+{\it periti}
>     (experts)} text after.
>
>     text before \index{animals+‘special kinds’} text after. Or
>     alternatively, \index[animals+special]{animals+‘special kinds’}
>
>     The setup for my register is a pretty standard one. The processor
>     is not for the 'periti' case above but I use it for book titles.
>
>     \setupregister[index][n=1,method={zc,pc,zm,pm,uc},style=WORD]
>
>     \defineprocessor[special][style=italic]
>
>     In the periti case it is the \it command that clearly interferes
>     with correct alphabetic positioning in the sub entry list. Placing
>     +periti in the key does not overcome that problem.
>
>     In the ‘special kinds’ case it is the initial single quote mark
>     (‘) that causes the problem. The item comes last in the sub entry
>     list. And if i include a key [special], then it comes first in the
>     sub entry list. Either way, it is out of the desired sorting order.
>
>     I believe I have followed the helpful suggestions of various ones,
>     but it is always possible that I have not fully understood those
>     suggestions. The reality is that at the moment the issue remains
>     unresolved for me. Any further wisdom out there to offer me?
>
>     Julian
>
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