The History- base class is an abstract class that is parent to numerous other classes that define cumulative tracking data about the objects in your application, including rule instances.

History instances identify date, time, and user who updated a work object, rule, or other object in the system. A history instance may also contain attachments, notes made by this user, or an internal copy of the entire instance as it was before the update. In some cases, the historical copy can be used to undo changes or roll back an object to its previous values and state.

For users, the value of the history is to promote accountability and to identify the sources of automatic and manual processing of the object.

Generally. application developers do not need to create History- classes explicitly. When you add a new concrete class under the Work-, Data-, or Assign- base class, the system automatically creates a similar class to contain history details of that class, using the new class name as the trailing portion of the History- class name.

Adding history instances

History classes are created automatically in many cases:

• Work objects — Instances of concrete classes derived from History-Work- class are created when a work object advanced through a flow, typically through the Work-.AddHistory activity. Others are added automatically. History are visible on the work history report, typically accessed from the History button () on the work object form. See the Pega Developer Network article PRKB-25196 How to control history instances written to the audit trail.
• Rules — Instances of the concrete History-Rule class are created when you create a rule (with Saveor Save Asafter New) when you save a rule into a RuleSet not requiring check-out, and when you check in a rule () into a RuleSet that requires check-out. These are visible from the  History Details   button display (on the History tab). The history instance for a checked-in rule contains the entire previous contents of the rule before update: see How to restore a previous state of a rule.
• Data — Instances of concrete classes derived from the History-Data- class are created when a form (such as the Operator ID form) is saved or when a Data Table row is saved.

In other situations where history is needed, your application can include an activity that calls the History-Add method.

Deleting History- classes

When you delete an empty concrete Work-, Data-, or Assign- class, the system deletes the associated History- class if it is also empty. R-11901

For a work object, the history display is sometimes called an audit trail.

Security audit feature

Using the optional security audit feature, your application can present in the History details display which values were added, updated, or removed from a rule or data instance. C-2644

	abstract class, audit trail, base class, compliance. ultimate base class
	How to use the developer toolbar Working with the PegaRULES database — Tables for History How to complete and use the History tab of a rule form How to enable security auditing for rule or data changes User portal basics — About work object history and attachments About Harness rules History-Add method
	Atlas — Standard properties in the History- class

Definitions — H