On 6/25/2018 17:52, Wolfgang Schuster wrote:
> \startmode[ebook]
> \setupbackend[export=yes]
> \stopmode
>
> \starttext
>
> \index{Knuth}\input knuth
>
> \index{Ward}\input ward
>
> \index{Zapf}\input zapf
>
> \startnotmode[*export]
> \completeregister[index]
> \stopnotmode
>
> \stoptext

Unfortunately, this does not suppress generation of index references in 
the exported output. Here is a snippet of the -div.html file generated 
by the example you provided:

    <div class="registerlocation index" href="#aut-1"
    onclick="location.href=&apos;#aut-1&apos;"><!--empty--></div>Thus, I
    came to the conclusion that the designer of a new system must not
    only be the implementer and first large--scale user; the designer
    should also write the first user manual.

and a snip of the output with the default css:

Thus the request for a (simple) mechanism to redefine or disable 
standard commands. There are commands other than \index that might also 
benefit from similar treatment.

-- 
Rik