A new property, pxCommitDateTime, records the time when a record or updated rule was committed to the database. This property also allows for incremental extracts when running BIX.
New property pxSaveDateTime
Valid from Pega Version 7.1.8
A new property, pxSaveDateTime, records the date and the time that an instance was saved with business changes to the database. This property is always used when an instance is saved, whether you are creating an instance or updating an existing instance. This property is not updated when an instance is moved from one system to another, and it is not updated during certain system management operations that do not change the content of the instance, such as column exposure.
All Pega product release notes can be found on their product pages.