[Boost-build] How do I import a path-constant or constant from a non-parent Jamfile?

Subject: [Boost-build] How do I import a path-constant or constant from a non-parent Jamfile?
From: Matthew Chambers (matt.chambers42_at_[hidden])
Date: 2012-01-26 11:04:12

I have a Jamfile hierarchy like:

data/reader/vendor/Jamfile
utility/api/vendor/Jamfile

I want to access variables declared in utility/api/vendor/Jamfile from data/reader/vendor/Jamfile. 
How can I do that?

Thanks,
-MAtt