Hi,
maybe you can help us understand, why you're asking this.
Either you have a certain understanding of payroll and related processes - than IMO you don't need to ask
or
you don't have a clue - in that case, start with the basics and keep clear of PA03.
Only that much.
The control record is used to keep track of the current status of each payrolll area.
Every program that is concerned with alteration or interpretation payroll related data (input or result) will read the control record and dependent on current status, will decide whether an action is allowed or not.
Maintaining and reading the control record is crucial to the integrity of the whole payroll process.
Best regards - Jörg