A game designer does not need to write or interpret XML schemas to work with the LevelEditor, but it is useful to understand their relationships to assets, game objects, and levels.
In general, a schema is an outline or diagram that describes an object. An XML schema uses XML elements and attributes to describe an object’s data structure. The LevelEditor uses this description to interpret objects presented as assets.
The LevelEditor uses a variety of XML schemas to interpret objects. For example, the LevelEditor can work with ATGI files because an XML schema is available that describes the data in an ATGI file. To interpret a particular object, the LevelEditor requires an XML schema that describes all objects of that type. For example, the ATGI schema describes the structure of any ATGI object; the LevelEditor refers to this schema whenever it manipulates any ATGI object.
By writing or annotating XML schemas, an XML programmer can add features such as new game object types, new, attributes, new resource slots for existing game objects, and support for additional types of assets.
For information about writing XML schemas to define additional game object types, see the LevelEditor Programming Guide or the ATF Programmer's Guide: Document Object Model (DOM) (available from https://github.com/SonyWWS/ATF/tree/master/Docs).