if
else
repeat
while
function
for
in
next
break
TRUE
FALSE
NULL
Inf
NaN
NA
NA_integer_
NA_real_
NA_complex_
NA_character_
…
and ..1
, ..2
etc, which are used to refer to
arguments passed down from a calling function. See the
/doc/manual/R-intro.html#The-three-dots-argument
manual for usage of these syntactic elements,
and dotsMethods for their use in formal methods.make.names
). They are allowed as non-syntactic
names, e.g. inside backtick quotes.