Key conflict management

[LJWatson]

How do different UAs factor into the processing model defined in 5.5.3 (Processing model)?

If the browser handles the processing, which ultimately seems likely since it'll have to update the accessKeyLabel based on the assigned accesskey, is the intention that it'll negotiate with any AT running at the time? If not, how/where does the hand-off between the browser and AT take place in the processing model?