diff --git a/docs/api/addclients.md b/docs/api/addclients.md
index 7a23091..2761d73 100644
--- a/docs/api/addclients.md
+++ b/docs/api/addclients.md
@@ -22,6 +22,11 @@ It is unknown as to what `100` represents, but it appears that all clients share
 #AP(callsign):SERVER:(network ID)::1:(protocol version):(rating):(real name ICAO)
 ```
 
+### When the SERVER asks to add a plane in your system ###
+It will send you as the following
+```
+#SB{recipient}:{who's plane}:FSIPIR:1::{plane type like F18}:6.77316:-1.96366:400.00000:4.7F50DEA9.97E5F402::{detailed aircraft description}
+```
 
 
 ## Removing clients ##
diff --git a/docs/api/pos.md b/docs/api/pos.md
index 761618a..fdcef38 100644
--- a/docs/api/pos.md
+++ b/docs/api/pos.md
@@ -28,14 +28,51 @@ Regardless of transponder mode, the altitude is always included in a position up
 
 A squawk code of `7500` (aircraft hijacking) will result in an immediate disconnection from the server.
 
-### Unknown fields ###
-
-The meaning of the following fields is unclear:
-
-* `(num1)` is a number of up to 10 digits.  It seems to begin with 4.
-* `(num2)` is an integer. There seems to be a wide range of values, anywhere between 1 and 3 digits, and can be positive or negative.
-
-
+### Now-Clear 'Unknown' fields answered by phoudoin ###
+
+> (num1) = pitch / bank / heading / onground value
+> a decimal sent as string whose value is the following unsigned 32bits binary number:
+> 
+> ```
+>  3         2         1         0
+> 10987654321098765432109876543210
+> <  pitch ><  bank  ><heading >OU
+> ```
+> 
+> * **U** bit:
+>   
+>   * unused
+> * **O** bit:
+>   
+>   * Aircraft onground indicator.
+> * **heading** 10bits field:
+>   
+>   * aircraft current heading, in degree
+>   * values range [0, 1023] (unsigned 10 bits number)
+>   * 1 = 360/1024 degree
+>   * 0 = magnetic north
+> * **bank** 10bits field:
+>   
+>   * aircraft current bank / roll angle, in degree
+>   * values range [-511, 512] (signed 10 bits number),
+>   * 1 = 180/512 degree,
+>   * negative value = right wing banking.
+> * **pitch** 10bits field:
+>   
+>   * aircraft current pitch angle, in degree
+>   * values range [-511, 512] (signed 10 bits number)
+>   * 1 = 90/256 degree
+>   * 0 = aircraft is at level
+>   * 256 = aircraft pitch is 90 degree up (aka skyrocket!)
+>   * negative value = down pitch
+> 
+> Onground aircrafts have usually 0 degree pitch and bank angles, their (num1) value is mostly heading encoded, a small value, very stable until they start taxiing.
+> 
+> On the contrary, airborne aircrafts have rarely perfect 0 degree pitch and banking angles, leading to big (num1) values.
+
+> (num2) = difference between Above Ground Level altitude (AGL) and Above Mean Sea Level (AMSL) altitude, as reported by aircraft barometric altimeter
+> 
+> Unit is feet, obviously.
 
 ## ATC ##