Per-package metadata. The optional 4th element marks an R-core / base package (base, stats,
parallel, the historical mva/nls/…): for these the version keys are the R releases during which
the package shipped with core R, so the set of versions is exactly the R versions it was part of core.
Per-package metadata. The optional 4th element marks an R-core / base package (
base,stats,parallel, the historicalmva/nls/…): for these the version keys are the R releases during which the package shipped with core R, so the set of versions is exactly the R versions it was part of core.