push @data, [@_] means: $_ was split into @_; if they said push @data, @_ the array @_ would append it's elements to @data. To append @_ as one unit to @data it must be given boundaries [ ]; this construct creates an array reference. This reference (a scalar) is stored in @data, holding the elements of @_ which are copied into [ ] at the moment of creation of [ ]. See perlreftut. Think of [@_] as "scalarifying" @_ into an (anonymous) array reference; an array can only hold scalars (single values, which references happen to be).

Wow. What noise ;-)

hoping not to have confused you further,
--shmem

_($_=" "x(1<<5)."?\n".q·/)Oo.  G°\        /
                              /\_¯/(q    /
----------------------------  \__(m.====·.(_("always off the crowd"))."·
");sub _{s./.($e="'Itrs `mnsgdq Gdbj O`qkdq")=~y/"-y/#-z/;$e.e && print}