goal argument to make in any automatic variable ? what is @[ $(origin $(*)) != 'undefined' ] && .. for ?

[andreas graeper]

hi,
i found in the end of a main-makefile

target: xxx
  @[ "$(origin $(*))" != "undefined" ] && echo "$($(*))"

`make -f that-makefile goal` is called from shell script

i tried to call a test makefile with and without goal

 make
and
 make <goal>
and i thought i could find the goal in $0 or $1 .. . is there a
automatic variable that tells me whether an explicit goal was given as
argument.

and what is $*. in which cases it can be != 'undefined' ( result from
$(origin $(*)) )

thanks in advance
andreas