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A general description is here.
Pasting into the script editor would sometimes change fonts and lose line breaks. (Reported by Bob Muenchen.)
Single and double quotations are now rendered using directional quotes in text conversions of R help (as they always have been in HTML, CHM and latex versions of the help). Note that directional double quotes are missing in Fixed
Font on some versions of Windows, and although the files will be rendered correctly in CJK locales using the builtin pager, they may not be in external pagers.
Rcmd Rdiff now ignores difference between smart single quotes and '. This will probably only work correctly in single-byte locales. (This is in addition to UTF-8 directional single quotes which the Unix version has for some time equated to '.)
getS3method() could fail if the method name contained a special character such as "+".