ALT 19 Direct reading uncorrected altimeter 
ALT 20 Direct reading corrected altimeter 
AT T 25 High altitude APR 
ALT 26 Low altitude APR 
ALT 21 High altitude statoscope 
ALT 27 High altitude geodolite 
ALT 28 Low altitude geodolite 
ALT 23 High altitude hypsometer' 
ALT 22 Low altitude statoscope 
ALT 27, 28 Expected for grouped geodolite points 
ALT 24 Low altitude hypsometer 
ALT 14 Laser dist„ measurement