Update README.md

README.md

@@ -83,7 +83,35 @@ The `dop_presence_flag` must be set to 1 if the `dop` field is present in the pa
 
 Transport of locally referenced 2D or 3D localisation. The "repère" is identified by an UID. 
 
+##### Payload general structure
+
+|    1B    | 4B  | 4B  | 0/4B | 0/4B  |    0/8B     |
+|----------|-----|-----|------|-------|-------------|
+| `header` | `x` | `y` |  `z` | `dop` | `repere_id` |
+
+The `x` field is a C-type float and is mandatory.
+
+The `y` field is a C-type float and is mandatory
+
+The `z` field is a C-type float and its presence is annouced in the `header`
+
+The `dop` field is a C-type float and its presence is annouced in the `header`
+
+The `repere_id` field is a 64-bit UID and its presence is annouced in the `header`
+    
+##### Header
+
+|        1b         |         1b          |            1b              |    5b    |
+|-------------------|---------------------|----------------------------|----------|
+| `z_presence_flag` | `dop_presence_flag` |  `repere_id_presence_flag` | reserved |
+
+The `z_presence_flag` must be set to 1 if the `z` field is present in the packet (3D localisation).
+
+The `dop_presence_flag` must be set to 1 if the `dop` field is present in the packet.
+
+The `repere_id_presence_flag` must be set to 1 if the `repere_id` field is present in the packet.
+
 #### Type 2 : Inter-node proximity
 
-Transport of raw distances (rangings) between pairs of nodes
+Transport of raw distances (rangings) between pairs of nodes. The ranging technology can be specified.