[R] How is the binding for a super assignment made visible?

[morphwj at comcast.net]

The statement Globals <<- list() in the body of a function in a package was intended to write an empty list to the R workspace to collect results during the computations of the function.  A package name space has not been specified.

The package appears to function correctly, but

during the R CMD check of the package while "checking R code for possible problems ... NOTE",

no visible binding for '<<-' assignment to 'Globals' is displayed.

Can you tell in this case why the binding needs to be visible?  What statement might do that?  A specific reference in the R manuals would be appreciated.

Bill Morphet
ATK Space Systems, Launch Systems, Nozzle Structural Analysis