All filters that are built using the Filter Builder are automatically converted to Collaborative Application Markup Language (CAML). The benefit of CAML is that it applies the filter to list items before they are collected and stored by the web part, which can improve the web part’s performance. This is particularly beneficial when Data Displays search through a large number of lists to locate data, yet the amount of data returned could be small. It is also useful for more complex filtering.
You do not need to know how to write CAML code; the conversion will be done automatically. However, if you prefer to manually define a CAML filter or if the filter you want to create is too complex for the Builder GUI, you can select the Manual Filter radio button and access an entry field.
For more information about CAML, please refer to these URLs:
•http://msdn.microsoft.com/en-us/library/ms948028.aspx