Re: Feature request: multilevel indexing for TeX

[arnold]

Hi.

> * What happens if there is an index entry with no secondary term and an 
> identical index entry with a secondary term, e.g.
>
> @cindex foo
> @cindex foo @sub bar
>
> I think that both should be kept.  When I tested it with C texindex, one 
> of them was lost in the output.

I agree. We need to put together a "torture test" for texindex.

> * Do we keep @defop, and the other commands in texinfo.tex currently using 
> \dosubind, as creating single-level index entries?  I assume yes, even 
> if it was different before: no-one to my knowledge ever complained that 
> the behaviour changed, and it is more stable to keep things as they are, 
> even if in the past they were possibly different.  I suspect not many 
> are using these commands anyway.

I agree.

> Perhaps sort keys could be generated for primary, secondary and 
> tertiary entry text separately, and simply concatenated to produce the 
> sort key.

Separate keys, yes. Concatenataed, no.

> Maybe a special marker character could be output that texindex treats 
> specially: e.g. the above would be output as
>
> \entry{aa^_a}{1}{aa}{a}
> \entry{aa^_z}{3}{aa}{z}
> \entry{aah}{5}{aah}
>
> where ^_ is a 0x1F byte.

Yes, perfect, that's real easy to handle in awk.

> Using a space instead may even suffice:
>
> \entry{aa a}{1}{aa}{a}
> \entry{aa z}{3}{aa}{z}
> \entry{aah}{5}{aah}

I don't like that; if a sort key has spaces it, we're in trouble.

> * If somebody uses contradictory sort keys for the primary text: this 
> doesn't make sense, and unpredictable results are acceptable: e.g.
>
> @cindex foo @sortas{aaa} @sub one
> @cindex foo @sortas{zzz} @sub two
>
> Here the "foo" entries could be sorted as "aaa" or "zzz" and it wouldn't 
> matter much which.

Right. Garbage In, Garbage Out. No problem with that.

> * We cannot actually use @sub because this clashes with the subscript 
> command.  Using @tab or @indent instead may be a possibility.

@indent makes sense, since that's what happens on the page, but I
can live with @tab also, or something like @subind might be good too.
I don't have strong feelings, as long as it makes reasonable sense
and is easy to convert an existing entry to it.

This is starting to come together in my head, at least in terms of what
texindex will need to do.

Thanks!

Arnold