TITLE(NA @@ Not Available Value)
USAGE(
NA
is.na(x)
as.na(x)
)
ALIAS(NA)
ALIAS(is.na)
ALIAS(as.na)
DESCRIPTION(
LANG(NA) is a logical constant of length 1 which contains
a missing value indicator.  LANG(NA) can be freely coerced to any
other vector type.
PARA
LANG(as.na) ignores its argument and returns the value LANG(NA).
PARA
LANG(is.na) takes a vector argument and returns a logical vector
of the same length containing LANG(TRUE) for those elements marked
LANG(NA) and LANG(FALSE) otherwise.  LANG(dim), LANG(dimnames) and
LANG(names) attributes are preserved.
)
SEEALSO(
LANG(LINK(complete.cases)).
)
