xml:lang in XAML
XAML xml:lang property
Notice the xml:lang placed at the root element of the XAML file. This property describes the culture of a given element and its children. This value is used by several features in WPF and should be changed appropriately during localization. This value changes what language dictionary is use to hyphenate and spell check words. It also affects the display of digits and how the font fallback system selects which font to use. Finally, the property affects the way numbers are displayed and the way texts written in complex scripts are shaped. The default value is “en-US”.