Popular for a time, some applications utilize XML formatted messages for intersystem and inter-application communication.
Example:
Define an XML formatted datastore layout using a Document Type Definition (DTD) that exists in file balance_alert.dtd. Define the target datastore file alert.msg that uses the balance_alert.dtd as its format.
DESCRIPTION XMLDTD /home/sqdata/balance_alert.dtd AS BAL_ALERT;
DATASTORE /home/sqdata/alert.msg
OF XMLCDC
AS T_BALANCE_ALERT
DESCRIBED BY BAL_ALERT;