some question about automatic variables

[loody]

Dear all:
Below are my questions:
1. There is a section, 10.5.3 Automatic Variables, which explain the
meaning and usage of automatic variables.
But I cannot find the usage of $< in the manual.
Would anyone tell me where it is?

2. in that section, there is an example say "if "$@" is "dir/foo.o",
$(@D) will be "dir""
does that mean if our makefile as below:

dir/foo.o dir/abc.o dir/def.o : header.h
    commands

and $@ in the commands will be dir/foo.o and $(D@) will be dir?

-- 
Regards,
miloody