...
Uploaded messages must not be larger than 2MB (uncompressed). You can read more about how we respond to a message larger than 2MB this on the herewithin the 'Developer Guide' on this page.
Bundling Updates
Rate, Availability or Restriction updates must be bundled in instances where the values for consecutive dates are the same. For example, if you are changing a rate of $120 from the 1 July - 14 July you must bundle the message. More information on bundling is included within the 'Developer Guide' on the bundling updates best practice page.
...
Request messages (Availability, Restrictions & Rates) must ONLY CONTAIN data relevant to the action being performed in your PMS. For example, if a PMS user is changing the availability of a room in the PMS, you must only send the availability update and no other rate or restriction messages. No unchanged dates should be included in these request messages. More information on each message structure will be contained in the pmsXchange 'Developer Guide'. More details on deltas can be found here.
In addition to this, these updates MUST be sent to pmsXchange V2 in as close to real-time as possible. Updates should be sent within 2 minutes of the change occurring in your PMS.
...