Consolidate Bill Group Electronic Invoices

Dears Experts,

Please help on information under Consolidate Bill Group in Project module.

1.We have the option to select Electronic Invoices :YES,NO and Blank

What is the use of this option if client will select? for consolidate bill group.

2.Consolidate bill Group ,we can use for Project Contracts and Project Billing.

If business will select option : Project Contract or Projects

How we can use above options.

Thanks

Sudhakar Dasari