1 files changed, 14 insertions, 17 deletions

diff --git a/modules/README b/modules/README
index 537ff2d..54f816c 100644
--- a/modules/README
+++ b/modules/README
@@ -7,27 +7,24 @@ There are 3 kinds of pdp messages:
 [pdp register_rw <packet_id>]
 [pdp process]
 
-An object can receive a packet by catching the 3 kinds of messages:
+Together they form the pdp protocol. An object can receive a packet 
+by catching the 3 kinds of messages:
 
 When a register_ro message is received, the object can call 
-pdp_packet_copy_ro(packet) to reseve a read only copy for itself.
-The only operations on the packet at that time are read only
-operations. 
+pdp_packet_copy_ro(packet) to reserve a read only copy for itself.
 
 The same goes for handling the register_rw message. You can
 reserve a read/write copy by using pdp_packet_copy_rw(packet)
 
 When a process message is received, the object is allowed to start
-processing the data.
-
-In the register_ro or register_rw phases, the object can inspect
-the packet to see if it wants to register it (using pdp_packet_header
-and pdp_packet_data operations) but it is not allowed to allocate other objects
-in that phase. This is only allowed in the process phase. (or after
-the receiving packet is registerd.) 
-
-An object can send out a pdp message using the outlet_pdp(outlet, packet)
-function. This sends out these 3 messages in sequence. It is best to
-unregister a packet using pdp_packet_mark_unused(packet) before sending it out,
-if it is no longer used by the sending object. This eliminates one extra 
-copy operation on the data.
+processing the packet data end send the resulting packet(s) out.
+
+To send out a packet, use the pdp_packet_pass_if_valid(outlet, &packet)
+method. It passes a packet, and sets the reference to -1 (the undefined
+packet id).
+
+
+If you want to write pdp externs, consider using the pdp_base object
+to derive your object from. Have a look at pdp_add, pdp_gain, pdp_noise
+to see how to do this.
+