login_hint?

[Cantor, Scott]

Also, since it is not in fact precluded by the binding specifications, adding a feature to capture other named parameters and store them in a context is certainly a plausible feature-add.

Would I personally deploy this? Probably not, because I'd be letting a vendor dictate a proprietary add-on instead of pursuing it through proper standardization. But I'm not forced to deploy it.

-- Scott