diff --git a/libowlps/owlps.h b/libowlps/owlps.h
index d9a00aa..b28e324 100644
--- a/libowlps/owlps.h
+++ b/libowlps/owlps.h
@@ -78,6 +78,11 @@ typedef struct _owl_request
   uint8_t mobile_mac_addr_bytes[ETHER_ADDR_LEN] ; // MAC of the mobile
   owl_timestamp request_time ; // Request ID (timestamp on the mobile)
   uint16_t nb_info ; // Number of (listener MAC;signal strength) couples
+  /* Calibration data */
+  float x_position ;
+  float y_position ;
+  float z_position ;
+  owl_direction direction ;
 } owl_request ;