The following types of help are available:
Plain text help
HTML help pages with hyperlinks to other topics, shown in a
(Where possible an existing browser window is re-used: the macOS
GUI uses its own browser window.)
If for some reason HTML help is unavailable (see
startDynamicHelp), plain text help will be used
help only, typeset as PDF --
see the section on ‘Offline help’.
The ‘factory-fresh’ default is text help except from the macOS
GUI, which uses HTML help displayed in its own browser window.
The default for the type of help is selected when R is installed --
the ‘factory-fresh’ default is HTML help.
The rendering of text help will use directional quotes in suitable
locales (UTF-8 and single-byte Windows locales): sometimes the fonts
used do not support these quotes so this can be turned off by setting
options(useFancyQuotes = FALSE).
topic is not optional: if it is omitted R will give
If a package is specified, (text or, in interactive use only,
HTML) information on the package, including hints/links to suitable
lib.loc only is specified, a (text) list of available
help itself if none of the first three
arguments is specified.
Some topics need to be quoted (by backticks) or given as a
character string. These include those which cannot syntactically
appear on their own such as unary and binary operators,
function and control-flow reserved words (including
next). The other
words can be used as if they were names, for example
If multiple help files matching
topic are found, in interactive
use a menu is presented for the user to choose one: in batch use the
first on the search path is used. (For HTML help the menu will be an
HTML page, otherwise a graphical menu if possible if
getOption("menu.graphics") is true, the default.)
Note that HTML help does not make use of
lib.loc: it will
always look first in the loaded packages and then along