Data pages (known as "declare pages" and "declarative pages" in Pega Platform™ versions before 7.x), provide on-demand access to data from your business processes while insulating the business processes from the actual integration details that are required to connect to the physical sources.
Data pages store data that the system needs to populate work item properties for calculations or for other processes. When the system references a data page, the data page either creates an instance of itself on the clipboard and loads the required data in it for the system to use, or responds to the reference with an existing instance of itself.
Data pages obtain the data from external sources by connectors, from report definitions that generate queries of the Pega Platform database, or from other sources; and might use data transforms to make the data fully available where it is needed.
The name of a data page starts with the prefixes D_ or Declare_ . On the clipboard, the contents of data page instances are visible, but are read-only.
The Data Explorer in Designer Studio lists all the data pages that are available to your application. By using the Data Explorer, you can quickly add data pages and data object types (classes).