Allow only authors / presenters to register for participation

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

You can define a constraint and limit participant registration to authors or presenters.

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 to 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 particular user shall be allowed to register for participation.

Please go to:
Overview => Settings => Settings for User Registration => Main Setup for User Registration and Management
... and scroll down to the section "Settings of Specific User Rights" and activate the option "Show User Statuses 'Approved to Submit', 'Approved to Participate' and 'Registration Fees Waived'".

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

You can now prevent anyone else from registering by setting a deadline in the past here:
Overview => Settings => Main Settings for Participant Registration

Hint:
You will find information on how to limit the number of participants here:
Limit the total number of all participants (from all participant groups)