Following on from my semantic_id proposal, here are some illustrative messages.
GNSS
@semantic_id 1
uint3 instance
uint3 status
uint32 time_week_ms
uint16 time_week
int36 latitude # in 1e-8 degrees
int36 longitude # in 1e-8 degrees
float32 altitude
float32 yaw
uint16 hdop
uint16 vdop
uint8 num_sats
float32 velocity[3]
float16 speed_accuracy
float16 horizontal_accuracy
float16 vertical_accuracy
float16 yaw_accuracy
Magnetometer message
@semantic_id 2
uint3 instance
int16 field_mgauss[3] # in milliGauss
Barometer message
@semantic_id 3
uint3 instance
float32 pressure # Pa
int16 temperature_cdeg # centidegrees C
Differential pressure
@semantic_id 4
uint3 instance
float32 diff_pressure # Pa
int16 temperature_cdeg # centidegrees C