fo:character and hyphenation

Spec says:


6.6.3 fo:character


Common Usage: 

The fo:character flow object represents a character that is mapped to a
glyph for presentation. It is an atomic unit to the formatter.

[skiped]
 
[7.9 Common Hyphenation Properties] 

The question is: how fo:character might be hyphenated?
Why this properties block is added to the fo:character spec?