Earlier quoted context omitted.
I thought that "pre-booking" means that you input all the available data related to a document into some computer system, but you do not finalize & accept the document yet -> so some of the data can still be changed in the future without consequence (for example: when some issue is explained with a supplier). Pre-booking is the initial step before a complete booking.
Agreed. Except when it isn't :) Ticket agencies use 'pre-booking' to book the first tiny tranche of tickets. And HR departments seem to love 'pre-authorization' to get... authorization for holidays, or purchasing, and so on.
eg you can make on the day bookings or call up HR to say you've got dave from forklifts incorporated on the phone and you need the company card immediately.