Allow only authors / presenters to register for participation

We have only limited space for participants and want to allow all authors to register first / close the registration for all other persons, as we are running out of space.
How can we do this?

Please go to:
Overview => Settings => Main Setup for Participant Registration
and enable the "Expert Settings" in the bottom navigation bar.

Now scroll down to "Participant Registration Options" and change the setting for "Constraint for the Registration for Participation".
Usually registration is open for all users. Here you can limit registration to submitting authors or to presenters, i.e., authors with an accepted submission who are either submitting authors or recorded as presenters for the submission.

Please test your settings.

Please note that you can also choose directly which user shall be allowed to register for participation.

Go to
Overview => Settings => Settings for User Registration => Main Setup for User Registration and Management
scroll down to "Settings of Specific User Rights" and
and activate the option "Show user statuses "Approved to submit" and "Approved to participate"

Now you can give users the status "Approved to Participate" if you edit the user details. Users with this status can register even if the participant registration phase is disabled (so this setting is even more selective than the above).

You can now deactivate the phase for registration for participation for all other persons here:
Overview => Settings => Main Settings for Participant Registration

You will find information on how to limit the number of participants here:
http://www.conftool.net/ctforum/index.php/topic,222.0.html