Help required to understand the relationship between Assignments and Pay Elements

 hi all ,

I have been trying to understand the relationship between the Assignments ( Per_all_assignments_f ) and Pay elements ( pay_elements_entries_f ) . The pay elements are tagged based on the   assignment_id  of  per_all_assignments_f .

I have come across a situation where i am confused as to know how exactly are these two dependent .

Scenario :

i have three pay elements links  say

1) AB1   -- the eligibility criteria of this link  is   payroll_id = 61 .

2) AB2   -- the eligibility criteria of this link  is payroll_id=61  and people_group_id = 94

2) AB3   -- the eligibility criteria of this link  is payroll_id=61  and people_group_id = 94