Assuming an author specifies lang for the page or a passage, and that there's a mapping from the value of lang to a Microsoft Locale ID, wouldn't mapping it via UIA_CultureAttributeId at least make it easier for TTS engines or other AT to consume, as opposed to relying on heuristics? Does mapping it like that have a cost?

I guess the same question goes for mapping dir via UIA_TextFlowDirectionsAttributeId?

@boggydigital, any perspective?

Few things changed since asking the question - at the very least Narrator is considering supporting mixed-language texts and I'm sure other ATs would be interested as well to support full Microsoft Office document fidelity. For the Edge web platform this would be exposed in two ways (identical values, only difference is how you get them):

• On objects in the UIA tree this is exposed as UIA_CulturePropertyId (https://msdn.microsoft.com/en-us/library/windows/desktop/ee684017(v=vs.85).aspx)
• On the text ranges obtained with TextPatttern through UIA_CultureAttributeId (https://msdn.microsoft.com/en-us/library/dd757492(v=vs.85).aspx)

Both values are LCIDs (https://msdn.microsoft.com/en-us/library/cc233965.aspx).

While mapping those value we've realized one complication - HTML attributes are not inherited and to implement this in a way that makes sense we walk the tree to find the nearest ancestor with lang attribute. I don't think we've tried Firefox, but in Chrome on Windows at least I believe Blink maps lang attribute to (non-standard) CSS -webkit-locale property and gets cascade for free. We didn't check but I won't be surprised if Blink actually maps -webkit-locale and not lang itself.

As for UIA_TextFlowDirectionsAttributeId as a mapping for dir attribute - that does make sense, no objection.

Jason, let me know if I should capture both attributes in the mapping specification for UIA - I'm happy to.

Thanks @boggydigital. I've updated those mappings in the above commit. Closing, but if the language needs tweaking, we can do that.