Used by the routines at Update_Berk_State, Update_Timed_Events, Handle_Berk_Action, ScriptRoutine_AnimateTrapDoorBerk, Update_Drutt, Update_Entity_Slot, Test_ThingUpstairs_Overlap, ScriptRoutine_TaskThreeQueueSound, Update_Heater, ScriptRoutine_TaskFourTickOfferItem, ScriptRoutine_TaskFourBerkOverlap, Update_Ghosts, ScriptRoutine_VatQueueSound, ScriptRoutine_VatClearBit6AndReset, Print_EncodedMessage, GraphicLayoutRoutine_SetPendingSound, Clear_AttributeFile, Close_TrapDoor, Open_TrapDoor, ScriptRoutine_MoveRight and ScriptRoutine_MoveDown.

Queue a sound index in PendingSoundIndex for Play_QueuedSound. If bit 7 of A is set, force the queue (replace any pending sound). Otherwise keep the existing pending sound when one is already waiting Play_QueuedSound forms the parameter pointer as base 63751 plus index×8. That base address 63751 is the operand byte of the busy-check JR NZ, and it is never read as a sound parameter because indexes start at 1 (so the first block is at Table_SoundParameters).