[yocto] [opkg-utils] Question: why update-alternatives from opkg-utils chooses /usr/lib to hold database?

[ChenQi]

Hi All,

Recently I'm dealing with issue from which some discussion raises.
I'd like to ask why update-alternatives from opkg-utils chooses /usr/lib 
to hold its alternatives database?
I looked into debian, its update-alternatives chooses /var/lib by default.
Is there some design consideration? Or some historical reason?

Best Regards,
Chen Qi