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A general description is here.
Saving to PDF from the menu of a ‘windows()’ device used defaults for ‘family’, ‘fg’ and ‘bg’ from ‘ps.options()’ rather than ‘pdf.options()’ (but the factory-fresh defaults were the same).
‘R CMD build’ no longer attempts to preserve file permissions on Windows, because Windows (unlike POSIX-compliant OSes) stops read-only files being deleted in version-control directories.