What does the unit of measurement mean old?

I have a new watchface on my HUAWEI Watch GT and there's the old unit of measurement, which is currently 56.

Can anyone tell me what that is?

Compare with other watch faces what is given there at number 56.

Alt = Altitude = altitude.

That should stand for altitude. The height above sea level.

It is probably the "Altitude", the height difference you have covered.

That was an answer, not a comment…

Alt - height

https://de.wikipedia.org/...6henmesser

this is how the altitude is specified in airplanes

Altitude likely, i.e. Above sea level or ground (probably the former).

But the unity is missing. Feet or meters would be obvious, but one can't tell you.