+=item %s() is deprecated on :utf8 handles
+
+(W deprecated) The sysread(), recv(), syswrite() and send() operators
+are deprecated on handles that have the C<:utf8> layer, either
+explicitly, or implicitly, eg., with the C<:encoding(UTF-16LE)> layer.
+
+Both sysread() and recv() currently use only the C<:utf8> flag for the
+stream, ignoring the actual layers. Since sysread() and recv() do no
+UTF-8 validation they can end up creating invalidly encoded scalars.
+
+Similarly, syswrite() and send() use only the C<:utf8> flag, otherwise
+ignoring any layers. If the flag is set, both write the value UTF-8
+encoded, even if the layer is some different encoding, such as the
+example above.
+
+Ideally, all of these operators would completely ignore the C<:utf8>
+state, working only with bytes, but this would result in silently
+breaking existing code. To avoid this a future version of perl will
+throw an exception when any of sysread(), recv(), syswrite() or send()
+are called on handle with the C<:utf8> layer.
+