The several responses to my floundering with the register have been very 
helpful, though I would have to confess that I have ended up 'messing 
with' things (suggested by Hans re the [key]) and getting a satisfactory 
result in almost every case without always understanding why. But I can 
say that I have the 'sorting' issue resolved if it is a main entry, 
including if that entry is surrounded by quote marks or has one part of 
that entry formatted differently (e.g. italics).

But I don't seem able to apply this to subentries! I cannot solve the 
sorting of subentries that have special features (e.g. I might have 
needed italics for part of a subentry, or the subentry is surrounded by 
quote marks).

Here are my two situations (and in each case they appear out of 
alphabetical order in the subentry list):

1. \index{animals+‘special kinds’}: in this case ‘special kinds’ appears 
in the subentry list at the bottom of the list, after one that starts 
with 'v'. I 'messed with' this by adding keys, e.g., \index[Animals] 
etc. but  the item disappeared from the index altogether.

2. \index{Plenary Council+{\it periti} (experts)}: in this case it is 
the italicised /periti/ that appears out of place, after the letter 'i' 
rather than after 'p'. Again I tried putting various keys but this did 
not help.

I guess my confusion is this: I assumed that the [key] establishes the 
literal string which determines sort order. That seems to be the case 
for a main entry. How do I get it to work for a subentry?

Julian

On 29/1/22 21:39, Hans Hagen wrote:
> On 1/29/2022 11:02 AM, jbf via ntg-context wrote:
>> Thanks for this response. I'll have to work on this (but tomorrow... 
>> it's late at night for me at the moment). I can see part of what you 
>> mean: I can use, for example \index[myindex]{\it Book title} (Book 
>> Author) and get the correct result, but not sorted properly, so I 
>> have to understand how, as you say, to 'set the sort entry to the 
>> unformatted version' which is not clear to me at the moment. I'll 
>> tackle it on the morrow when I'm thinking more clearly!
> there is key and entry with key between []
>
> when sorting, the key wins but because there can be duplicates the 
> entry itself is also part of the final sort key
>
> the accumulates sort key is sanitized and after that sorting happens 
> in several stages (these can be defined / adapted) according to 
> language, taking numbers into account and finally using the unicode 
> ordering ...
>
> you can fool the system by messing with the [key]
>
> it's not the easiest subsystem (but it has a long history ... as with 
> many subsystems the principles are not much different than mkii and 
> the code seldom changes but of course evolved)
>
> Hans
>
>
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>                                           Hans Hagen | PRAGMA ADE
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