For forward compatibility with new WAI-ARIA properties in future versions, user agents SHOULD expose all properties not in the table below as a text string, removing the "aria-" prefix from the name, if the API supports it. For example, aria-foo="bar" would be exposed with a text string foo=bar in UIA, since aria-foo is not a currently known WAI-ARIA property. The following list specifies the accessibility APIs for exposing properties as text strings.
◦MSAA:
not supported
  ◦IAccessible2: expose as an object attribute pair ( property:string) 
  ◦UIA: expose an object attribute pair in AriaProperties (property=string) 
  ◦ATK/AT-SPI: expose as an object attribute pair (property:string) "