What does Ex"de" protection method really mean?

[olame]

Does anyone know what Ex"de" hazardous area equipment protection really mean?.
Ex"d" means flame-proof while Ex"e" means increased-safety, these are based on two different principles hence I am a little confused on how the two can be combined together for the same equipment.

 

[hollandhvac]

In addition to above, the EX d means that for an electrical motor the casing is strong enough to hold an explosion inside, but it may mean that the motor does not work any more.

The EX e is refering to the power connection to the same motor.

Also see att. document for much more info