page
A character string indicating what page to open. The default
"webpage" will open the main webpage, "errata" displays the
Errata sheet for the book, and "primer" fetches and displays
the primer for R.
script
If set, this will open an R script for one of the chapters
in the book in a browser window, or a script from one of the
chapters in the R Primer. Possible values are "chapter1",
"chapter2", ... "chapter12", "appendix" for chapters and
appendix from the book, or
"primer0", "primer1", ... "primer12", "primerappendix"
for material corresponding to the R primer.