How does “Proformas, drafts and the plan” work on the Payment Runs page?

Two folded sections sit above the bills on Build run: Proformas to pay — advances asked for before any bill exists, each its own line in the run and the bank file, posted as Spend Money to the company's proforma account — and Draft bills, bills still in BillScan without a GL or project that can nevertheless be paid now and are posted as a prepayment to be allocated once the bill is pushed. Planning is the third place a bill can wait: moved there from Build run with a note, grouped by supplier under each paying company, its status worked out from the bill's own state, and moved into a run when its day comes. The plan is also the workbook a director reads: a supplier summary per company with the left-to-pay as a formula. Where: Payment Runs (/accounts/payment-runs).