What is the usage or functionality of the contract line number in bill plan person override section

Summary:

Content (required):

Contract >> Billing Tab >> Bill plan OR Revenue Plan >> Schedules and Overrides Tab >> Person Rate and Discount Overrides Section

What is the usage or functionality of the contract line number here?

e.g. Contract have 2 lines L1 and L2 and two Bill plans BP1 (Rate based) and BP2 (Amount based).

L1 is assigned BP1 and L2 is assigned BP2.

Now, in the BP1, Person rate section, let say we select the contract line L2 and defined an person override rate.

But, There is no impact on the invoicing of L1. It will invoice with the override rate of BP1, even if the contract line for the override record is L2.