"The serial numbers and titles under chapters are always aligned by the central edge of the binding line side" should refer to the table of contents, if so, it means your "chapters" (such as the first and second sections, etc. ) and its following tables should be centered on the left (one side of the binding line). The so-called version center refers to the main content area of the directory, taking the heart as an example:

The first chapter:

the first paragraph

One,

Two.

Section 2:

Chapter 2:

The first section:

Section 2:

One,

Second,

The above version refers to the content area behind the joint. In other words, if your chapter title is indented, all the subheadings under your chapter should be aligned with the chapter title.