The first layer is "one, two, three"

The second layer is "(1) (2) (3)"

The third layer is 1.2.3.

The fourth layer is (1)(2)(3)

The fifth floor is ① ② ③.

Extended data:

1, Arabic numerals followed by black dots;

2. There is a pause after Chinese characters and numbers;

3. Use commas after "first", "second" and "third";

4. No pause, comma, etc. are added to the serial numbers in brackets and circles;

5. There is no need for punctuation marks after the first part, the first chapter, the first section or the first part, and only one Chinese character position is needed between the first part and the following text.

6. Generally, other bullets are no longer used before and after the numerical serial number.

References:

Baidu Encyclopedia-Serial Number