This is an example

Jurgen,
Good catch!

This is surely a use-case we overlooked there.

To get around things I would propose to add a @sub-name attribute to provide an arbitrary suffix.
Then the implementation class could just (without connecting dots) add that to the table-name.

@field could be kept for backwards compat (and more semantic editing) and stored in the same member (by prefixing with dot at config time)

@field and @sub-name should be exclusive though (using both should throw a config-exception)

Changes to svn-head that implement this new behaviour are in revision 659
(see http://svn.cocoondev.org/viewsvn?rev=659&root=xreporter&view=rev)

I did some additional tests and noticed how this new feature can get you into trouble:

Steps are managing the temptables and are dropping them out if the step is restarted. This will also drop associated indices.

This is good news: you can just re-create the index after re-creating the table when re-visiting the step.
However this also means that you should always create the index IN THE SAME STEP as creating the table. If not you could be retrying to create an index that already exists.

(Adding a warning to the docs about this)