[css3-selectors][selectors4] "Child combinators" in plural?

Something that's been bothering me for a good while now: the section of 
the Selectors spec which describes the one and only child combinator is 
titled "Child combinators", in plural (seen in levels 3 and 4).

This contrasts with the preceding section, "Descendant combinator", and 
the next two sections in Selectors 4 for "Adjacent sibling combinator" 
and "General sibling combinator". (In Selectors 3, these combinators are 
grouped in a section called "Sibling combinators".)

Since there's only one child combinator, just as how there's only one 
descendant combinator, is the plural "Child combinators" a mistake? Or 
is there some obscure reason behind it?

If it's just a mistake, I apologize for the nitpick ;)

-- 
Daniel Tan/BoltClock
NOVALISTIC • Stellar Software Development & Design
<http://NOVALISTIC.com>