The packing quantum — the smallest block of faders a bus tier may occupy. Every banked
tier (see BusTypeDescriptor.banked) is allocated in whole multiples of this, so no
tier ever ends part-way through a block: "no 5 matrices, it has to be 4 or 8".
Four is a half-bank, not a bank. A real bank happily mixes entity types — a Midas bank
showing 4 FX + 4 DCA is one bank holding two tiers' quanta — so 4 is the unit a tier packs
in, while SURFACE_BANK_WIDTH is the unit the surface pages in. Keeping the two
apart is what lets a lone half-bank pair up with another tier's instead of wasting a bank.
The packing quantum — the smallest block of faders a bus tier may occupy. Every banked tier (see BusTypeDescriptor.banked) is allocated in whole multiples of this, so no tier ever ends part-way through a block: "no 5 matrices, it has to be 4 or 8".
Four is a half-bank, not a bank. A real bank happily mixes entity types — a Midas bank showing 4 FX + 4 DCA is one bank holding two tiers' quanta — so 4 is the unit a tier packs in, while SURFACE_BANK_WIDTH is the unit the surface pages in. Keeping the two apart is what lets a lone half-bank pair up with another tier's instead of wasting a bank.