Configure Absence Batch Parameter - Under Additional Attributes : Basis for Accrual Calculation

Dear Experts,

Can somebody explain the functionality of

Basis for Accrual Calculation : Primary Assignment , Enrolled Assignment.

Path: My Client Group>Absence>Configure Absence Batch Parameter>Additional Attributes section>

Basis for Accrual Calculation : Primary Assignment , Enrolled Assignment

My Concern is about Enrolled Assignment.

Q1. Where we can enroll assignment?

Q2. In Which page we can enroll the assignment and how we can tag the plans to the enrolled assignment?

Q3. Is it one employee can have multiple active asssignment (if enrolled assignment treated as secondary assignment)?

I Would appriciate your response, Thanks for looking into this concept.

Ravindra