Xaml is defined in the Xaml Object Mapping Specification (referred to as ‘MS-XAML’ for short). The MS-XAML specification enables each application that uses Xaml to define its own vocabulary. Vocabularies are formally specified using the Xaml Schema Information Set, a data model defined by MS-XAML.
This specification defines the Xaml Schema Information Set information items for the Windows Presentation Foundation (WPF) Xaml Vocabulary. The information items in the Xaml Schema Information Set presented in this specification can be used in conjunction with MS-XAML to determine whether any particular Xaml instance or XML document is valid WPF Xaml.