diff --git a/kernel/netio.c b/kernel/netio.c
index d377745e..1e2bf3e3 100644
--- a/kernel/netio.c
+++ b/kernel/netio.c
@@ -24,6 +24,20 @@
 #include <metalsvm/syscall.h>
 #include <metalsvm/errno.h>
 
+/*
+ * This implements a netio server.
+ * The client sends a command word (4 bytes) then a data length word (4 bytes).
+ * If the command is "receive", the server is to consume "data length" bytes into
+ * a circular buffer until the first byte is non-zero, then it is to consume
+ * another command/data pair.
+ * If the command is "send", the server is to send "data length" bytes from a circular
+ * buffer with the first byte being zero, until "some time" (6 seconds in the
+ * current netio131.zip download) has passed and then send one final buffer with
+ * the first byte being non-zero. Then it is to consume another command/data pair.
+ */
+
+/* See http://www.nwlab.net/art/netio/netio.html to get the netio tool */
+
 #ifdef CONFIG_LWIP
 #include <lwip/sockets.h>