Based on the declarative constraints provided, the process underlying this data involves a series of activities related to the declaration process. 

The process starts with the submission of a declaration by an employee, followed by approval by the administration and then final approval by a supervisor. 

There are also activities such as request payment and handling payment that occur during the process. 

Various rejection scenarios are also included in the process, such as rejection by the employee, administration, supervisor, missing information, pre-approver, and budget owner. 

The process also includes activities related to saving the declaration and resubmitting it for approval by different stakeholders. 

The process is well-defined in terms of the order in which activities should occur (always before and always after constraints), restrictions on the co-existence of certain activities (never together constraints), and limitations on the number of occurrences for each activity (activity occurrences constraints). 

Overall, the process involves multiple stakeholders and activities related to declaration submission, approval, rejection, and handling payments.