No, that's actually just a plain Perl hash declaration. Watch:

#!perl

use strict;
use warnings;

my %hash = (
   one => 1,
   two => 2,
);

print "$_ => $hash{$_}\n" for keys %hash;
[download]

No error.
It's just "syntactic sugar" to make the declaration more uniform, I believe.
Hope this helped.
CombatSquirrel.