Each IHE XDS component needs to send ATNA Audit logs to the Audit Record Repository of the Multisafe Environment. A schema for a ATNA audit message can be found here: https://gazelle.ihe.net/XSD/IHE/ATNA/
More information about ITI-20 transaction used to send these messages can be found in the [ITI-20] Record Audit Event chapter in http://www.ihe.net/uploadedFiles/Documents/ITI/IHE_ITI_TF_Vol2a.pdf
Messages need to be send as SYSLOG to the specified endpoint (see Audit endpoints).