Re: Feature request: multilevel indexing for TeX

[Gavin Smith]

On Fri, Mar 01, 2019 at 02:25:29AM -0700, address@hidden wrote:
> > 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.

Unfortunately, writing ASCII control characters to files is not reliable 
and the results vary depending on the TeX installation and options.  
Likely "^^_" is written instead.

See 
https://tex.stackexchange.com/questions/8729/write-non-printable-ascii-characters-to-a-file.

The only reliable alternative seems to be to use a control sequence, 
thus:

\entry{aa\subind a}{1}{aa}{a}
\entry{aa\subind z}{3}{aa}{z}

I assume awk can deal with that fine.

It could be a "control symbol" instead, e.g.:

\entry{aa\!a}{1}{aa}{a}
\entry{aa\!z}{3}{aa}{z}

But I don't think we should use a control symbol for this as it could 
clash with real or future Texinfo commands that might occur in an index 
entry.

Whatever output is chosen, it would be good to check how existing 
versions of texindex deal with it: we should avoid completely breaking 
them if at all possible.