capitalization - Are chapter headings and other semantically smaller parts as the title capitalized?

I found the question Which words in a title should be capitalized? Regarding the number of answers votes and also according to my personal taste I like to capitalize titles. But what exactly are titles? Only the single main book title? What about other smaller semantic parts? Chapter headings, sub-chapter, ...

Answer

According to CMoS and APA (two popular style guides), some lower-level headings aren't capitalised in headline-style.

Chicago Manual of Style 16th edition (headings by level):

1. Centered, Boldface or Italic Type, Headline-style Capitalization


2. Centered, Regular Type, Headline-style Capitalization


3. Flush Left, Boldface or Italic Type, Headline-style Capitalization


4. Flush left, roman type, sentence-style capitalization


5. Run in at beginning of paragraph (no blank line after), boldface or italic type, sentence-style capitalization, terminal period.

APA (headings by level):

1. Centered, Boldface, Uppercase and Lowercase Headings


2. Left-aligned, Boldface, Uppercase and Lowercase Heading


3. Indented, boldface, lowercase heading with a period. Begin body text after the period.


4. Indented, boldface, italicized, lowercase heading with a period. Begin body text after the period.


5. Indented, italicized, lowercase heading with a period. Begin body text after the period.