[Rd] Confusion about Depends:, Imports:, Enhances:, import(), inportFrom()

[Michael Friendly]

In checking my vcdExtra package, the following NOTE newly appeared 
(R-Forge, using R version 3.0.1 Patched (2013-08-20 r63635))

Package in Depends field not imported from: ‘gnm’
   These packages needs to imported from for the case when
   this namespace is loaded but not attached.

In the DESCRIPTION file, I have

Depends: R (>= 2.10), vcd, gnm (>= 1.0.3)

In NAMESPACE:

# we are a vcd extension
import(vcd)

I've read 1.1.1 of R-Exts, but it is not clear to me whether I should 
also import gnm or change
the DESCRIPTION file to use

Imports: vcd, gnm (>= 1.0.3)

R-Exts says: The ‘Imports’ field lists packages whose namespaces are 
imported from (as specified in the
NAMESPACE file) but which do not need to be attached, but how can I tell 
if gnm needs to be attached?

Also, what is the difference between Imports: in DESCRIPTION and 
imports() in NAMESPACE?

-Michael

-- 
Michael Friendly     Email: friendly AT yorku DOT ca
Professor, Psychology Dept. & Chair, Quantitative Methods
York University      Voice: 416 736-2100 x66249 Fax: 416 736-5814
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