The ARI Sync -  Inventory (OTA) is used to notify a booking source of the inventory amount available at a specific hotel property.

The ARI Sync - Rates ( HTNG) is used to communicate the creation of new rate plans and modification of existing rate plans for one hotel for one rate plan.

The ARI Sync- Rates (OTA) is used to provide a notification of a new rate plan created for a hotel, and to synchronize the rate plan between systems for booking.

The OTA_HotelCacheChangeRQ message allows partners to query SynXis CR to identify rate and availability changes in SynXis CR, so that the partner can send a targeted shop to SynXis to get the updated availability.