Philips V24CT User's Reference Manual page 329

Installation Information
Switch position is on/off.
Contrast.
Alternating current.
Protective earth
Contains parts to be recycled
Contains parts which may not be put into the normal
waste disposal but must be recycled or dealt with as
chemical waste.
Altitude or atmospheric pressure
Temperature
Humidity
This symbol identifies the date of manufacture. The
date format is Year - Month, e.g. 1999 -07
1999 - 07
Monitor Installation and Patient Safety 11-13