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"supplier". Each actual reservation returns "supplier" identifier - the unique identifier of the booking in supplier's system. Normally this value should be further used in hotel voucher. ResID_SourceContext attribute identifies the supplier. It is not necessary to pass the "supplier" identifier in all following requests; only "client" is required.
You have to store all values of HotelReservationIDs in your system, and use it unchanged through whole booking's life cycle.
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