What Does Apple Watch's IPX7 Water Resistant Rating Really Mean?

Apple has revealed in its website a footnote as an explanation to its water resistant feature:

The footnote reads: 

"Apple Watch has a water resistance rating of IPX7 under IEC standard 60529. The leather bands are not water resistant."

What does IPX7 really mean? According to IEC 60529, "IP" which stands for "Ingress Protection" has two degrees of protection denoted by the first and second characteristic numeral:

• the first is degrees of protection against solid foreign object like dust 
• the second is degrees of protection against water with harmful effects

What does X really mean here? X indicates that it is being omitted therefore the enclosure of Apple Watch is only rated and designated by the second characteristic numeral. This means that the enclosure is unsuitable for exposure to water jets (denoted by numeral 5 and 6) unless dual coded like the following (the first four rows):

As for the bottom two rows, Numeral 7 and 8 denote temporary immersion and continous immersion respectively but in the case of "restricted" application such as IPX7 and IPX8 the enclosures are only suitable for respective immersion but not suitable for any water jetting.

Here is the detailed descriptions and test conditions for second numeral 5, 6, 7 and 8 :

The numeral 7 refers to test condition in the right-most column as "14.2.7". Here is the test description for 14.2.7:

An enclosure with height equal to or greater than 0.850m physically looks like the above but for the smaller Apple Watch, it means it can be at the bottom of that 1.000m below the water surface for the duration of 30 minutes and survive!

In conclusion the Apple Watch will be able to handle the following based on the above rating & testing: 

a) splashing and spraying during shower

b) temporary immersion of 1.000 meter underwater for less than 30 minutes

But please do not take it under strong water jets like that of the fireman's fire-fighting hose.