Casio 3069 Manual page 60

Barometric Pressure Differential Pointer
This pointer indicates the relative difference between the most recent
barometric pressure reading indicated on the barometric pressure graph
(page E-56), and the current barometric pressure value displayed in the
Barometer/Thermometer Mode (page E-54).
• Pressure differential is indicated in the range of ±5 hPa, in 1-hPa units.
• The barometric pressure differential pointer is not displayed when the
displayed current barometric value is outside of the allowable measurement
range (260 to 1,100 hPa).
E-58