+@cindex strings, replacing substrings
+@cindex replacing substrings
+@deftypefn {Function} {} REPLACE (@var{haystack}, @var{needle}, @var{replacement}[, @var{n}])
+Returns string @var{haystack} with instances of @var{needle} replaced
+by @var{replacement}. If nonnegative integer @var{n} is specified, it
+limits the maximum number of replacements; otherwise, all instances of
+@var{needle} are replaced.
+@end deftypefn
+