To answer my own question, after experimentation:

\index[key]{form::entry}
with
\setupregister[index][form][textstyle=\hskip1em]


A.

On Sun, Mar 18, 2012 at 12:38 PM, Alan Bowen <bowenalan03@gmail.com> wrote:

> Sorry: My effort escaped without a subject line.
>
>
> In placing the heads and subheads of indices, \index defaults to
>
> Head    locator
> Head
>     subhead    locator
>
> I need to get the subhead without repeating the Head, as in
> Head    locator
>     subhead    locator
>
> How can I do this? Is there some documentation on this that I can read?
>
> Alan
>
>