Requiement type IPC user exit

Hi all,

I am not to IPC user exits, have 2 basic questions regarding IPC exits.

1) If a requirment type IPC user exit is attached to some ("conditon type" of type 'manual') in a pricing procedure, What happens when the exit return's false?

2) If a requirment type IPC user exit is attached to some ("conditon type" of type 'manual') in a pricing procedure, What happens if we write some error to the logger class? Will it halt the processing of the CRM sales document.?

Kindly reply !