+ my $rcv = mrecv local %SIG, cb => sub { ... };
+
+ In the callback, $_[0] is the sender's PID (or 0 if the sender wanted to
+ stay anonymous) and $_[1] is the message received.
+
+ "mreset"
+ mreset $rcv
+
+ Resets the state of the receiver $rcv. Useful to abort transfers.
+
+ "mbusy"
+ mbusy $rcv
+
+ Returns true if the receiver $rcv is currently busy with incoming data,
+ or false otherwise.
+
+ "mlastsender"
+ mlastsender $rcv
+
+ Holds the PID of the last process that sent data to the receiver $rcv, 0
+ if that process was anonymous, or "undef" if no message has arrived yet.
+ It isn't cleared by "mreset".
+
+ "mlastmsg"
+ mlastmsg $rcv
+
+ Holds the last message received by $rcv, or "undef" if no message has
+ arrived yet. It isn't cleared by "mreset".