Schema for Object-Oriented XML (SOX) is a data description language designed with XML to add power and versatility to standard XML documents. With SOX, data becomes more intelligent, better-defined, and more readable to both humans and computers.

SOX benefits both the application developer and the document designer. It allows for the easy creation of structure definition modules, and permits different document structures to be reused in different settings. (SOX modules can even be traded between different companies, in a manner very similar to Java libraries.) SOX also expands document type definitions (DTDs) to be far more readable and usable than in standard XML.

SOX extends XML for e-commerce and distributed computing by adding strong typing, inheritance, global name spaces, etc.