For Data reference, are you looking for Reference properties? if yes then, The reference property can be used if you want to relate a property to another property, where both properties belong to same top-level page or are in different top-level pages. Reference property can be used instead of copying the another page.
However it depends on the usecase which may define later as which pattern you can use to access data page.
I already read this article about linked properties, it is more or less a database foreign key relationship. Anyway data reference - which you can define in data model of a case - is very similar, but what I can see in the database is that the complete reference page is stored as well, which costs additional disk space. For data references I still need to define another property which holds the unique key of the referenced page.
For me it is still not clear, when to use what. Currently I would say use only linked properties.
When we use linked properties, Pega performs a database lookup and retrieves the blob into the linked reference page (it is evident in the article as well). Even though we wanted one property value from BLOB, we are fetching the entire BLOB in memory. Hence, I think a data reference populated by a parameterized data page (which in turn probably performs a lookup via RD, thus retrieving only selected recrods) is better instead of using linked properties.
i think I got the point. With linked properties you just define a Foreign Key relationship. With data reference you can use Report Definitions in Data Pages to filter data with special criteria. It is more dynamically.