How to mark the pronunciation and tone of water?

Tone labeling of Chinese Pinyin has certain rules to follow. According to the introduction of [2], for the pronunciation of a single vowel, tone labeling is carried out according to the following rules:

Three vowels: A, O and E: Tones are marked according to the order in which the three vowels A, O and E appear.

I, U vowels: Tone symbols are directly marked on the vowels after I and U during tone calibration.

ü and I and U appear at the same time: Tone symbols should be marked on vowels after I and U, not on ü.

For the pronunciation of multiple vowels, the rules of tone labeling are as follows:

If there is an a in the vowel, mark the tone symbol on it.

If there is no A, see if there is an O, and if there is an O, mark it.

If there is no o, mark it on e.

For example, the Chinese character "water", its pinyin is "shuǐ". Where "sh" stands for "sh" in Chinese pinyin, and the phonetic notation of "uǐ" should follow the above rules.

Since the vowels "u" and "ǐ" appear at the same time, the tone symbol should be marked after "ǐ". Finally, the pinyin label of "shuǐ" should be "Shu ǐ (shuai3)".