[Rd] DESCRIPTION: Imports: assertion of version?

[Henrik Bengtsson]

Hi,

from 'Writing R Extensions' [R version 2.11.0 Under development
(unstable) (2010-03-16 r51290)] one can read:

"The optional `Imports' field lists packages whose name spaces are
imported from but which do not need to be attached. [...] Versions can
be specified, but will not be checked when the namespace is loaded."

Is it a design decision that version specifications are not asserted
for packages under "Imports:", or is it a "lack of implementation"?
If a design decision, under what use cases do you want to specify the
version but not validating it?  Is it simply because there is no
mechanism for tracking the origin/package of the code importing the
other package, and hence we cannot know which DESCRIPTION file to
check against?

Thanks

Henrik