"I, (i), 1, a" respectively represent the first-level title, the second-level title, the third-level title and the fourth-level title in the paper.

Under "one, two, three, four"

Under items (1), (2) and (3) ..........................................................................................................................................................

Under 1, 2, 3 and 4, there can be four-level titles such as A, B, C and D. ..

In the new national standard, the serial numbers of the first, second and third-level titles are all represented by Arabic numerals:

First-class title: 1

Secondary title: 1. 1

Third-level title: 1. 1. 1

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