These functions take the output of the parse_Rd function
  and produce a help page from it.  As they are mainly
  intended for internal use, their interfaces are subject to change.
Rd2HTML(Rd, out = "", package = "", defines = .Platform$OS.type,
        Links = NULL, Links2 = NULL,
        stages = "render", outputEncoding = "UTF-8",
        dynamic = FALSE, no_links = FALSE, fragment = FALSE,
        stylesheet = "R.css", ...)Rd2txt(Rd, out = "", package = "", defines = .Platform$OS.type,
       stages = "render", outputEncoding = "",
       fragment = FALSE, options, ...)
Rd2latex(Rd, out = "", defines = .Platform$OS.type,
         stages = "render", outputEncoding = "UTF-8",
         fragment = FALSE, ..., writeEncoding = TRUE)
Rd2ex(Rd, out = "", defines = .Platform$OS.type,
      stages = "render", outputEncoding = "UTF-8",
      commentDontrun = TRUE, commentDonttest = FALSE, ...)
a filename or Rd object to use as input.
a filename or connection object to which to write the output.
the package to list in the output.
string(s) to use in #ifdef tests.
at which stage ("build", "install", or
    "render") should \Sexpr macros be executed? See the
    notes below.
see the ‘Encodings’ section below.
logical: set links for render-time resolution by dynamic help system.
logical: suppress hyperlinks to other help topics.
      Used by R CMD Rdconv.
logical: should fragments of Rd files be accepted? See the notes below.
character: a URL for a stylesheet to be used in the header of the HTML output page.
NULL or a named (by topics) character vector of
    links, as returned by findHTMLlinks.
An optional named list of options to pass to
    Rd2txt_options.
additional parameters to pass to parse_Rd when
    Rd is a filename.
should \inputencoding lines be written in
      the file for non-ASCII encodings?
should \dontrun sections be commented
      out?
should \donttest sections be commented out?
These functions are executed mainly for the side effect of
  writing the converted help page.  Their value is the name of the output
  file (invisibly).  For Rd2latex, the output name is given an
  attribute "latexEncoding" giving the encoding of the file in a
  form suitable for use with the LaTeX inputenc package.
Rd files are normally intended to be rendered on a wide variety of systems, so care must be taken in the encoding of non-ASCII characters. In general, any such encoding should be declared using the encoding section for there to be any hope of correct rendering.
For output, the outputEncoding argument will be used:
  outputEncoding = "" will choose the native encoding for the
  current system.
If the text cannot be converted to the outputEncoding, byte
  substitution will be used (see iconv): Rd2latex
  and Rd2ex give a warning.
These functions convert help documents: Rd2HTML produces HTML,
  Rd2txt produces plain text, Rd2latex produces LaTeX.
  Rd2ex extracts the examples in the format used by
  example and R utilities.
Each of the functions accepts a filename for an Rd file, and
  will use parse_Rd to parse it before applying the
  conversions or checks.
The difference between arguments Link and Link2 is that
  links are looked in them in turn, so lazy-evaluation can be used to
  only do a second-level search for links if required.
Note that the default for Rd2latex is to output ASCII,
  including using the second option of \enc markup.  This was
  chosen because use of UTF-8 in LaTeX requires version
  ‘2005/12/01’ or later, and even with that version the coverage
  of UTF-8 glyphs is not extensive (and not even as complete as
  Latin-1).
Rd2txt will format text paragraphs to a width determined by
  width, with appropriate margins.  The default is to be close to
  the rendering in versions of R < 2.10.0.
Rd2txt will use directional quotes (see sQuote)
  if option "useFancyQuotes" is true (the default) and
  the current encoding is UTF-8.
  the current locale uses a single-byte encoding (except C).
  (Directional quotes are not attempted in East Asian locales as they are
  usually double-width, which looks wrong with English text.)
Various aspects of formatting by Rd2txt are controlled by the
  options argument, documented with the Rd2txt_options
  function. Changes made using options are temporary, those
  made with Rd2txt_options are persistent.
When fragment = TRUE, the Rd file will be rendered
  with no processing of \Sexpr elements or conditional defines
  using #ifdef or #ifndef.  Normally a fragment represents
  text within a section, but if the first element of the fragment
  is a section macro, the whole fragment will be rendered as
  a series of sections, without the usual sorting.
# NOT RUN {
## Simulate install and rendering of this page in HTML and text format:
Rd <- file.path("src/library/tools/man/Rd2HTML.Rd")
outfile <- tempfile(fileext = ".html")
browseURL(Rd2HTML(Rd, outfile, package = "tools",
          stages = c("install", "render")))
outfile <- tempfile(fileext = ".txt")
file.show(Rd2txt(Rd, outfile, package = "tools",
          stages = c("install", "render")))
checkRd(Rd) # A stricter test than Rd2HTML uses
# }
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