What does the data of maximum altitude, average altitude, cumulative ascent and descent mean respectively on the Xiaomi Watch S3?

The information regarding the three kinds of data is as follows:
1. The highest altitude is the maximum altitude reached at any point during the movement;
2. The average altitude is the mean altitude over the entire duration of the movement;
3. The cumulative ascent/descent represents the total vertical distance climbed or descended during the exercise. Take the cumulative ascent as an example, when riding, there are 5 uphills on flat ground. After climbing each slope, the altitude will increase by 8 meters. Then the cumulative ascent after climbing these 5 slopes is 5x8=40m (the same is true for the cumulative descent).