my %newhash;

push @{ $newhash{IP} }, [ 'row 0, col 0', 'row 0, col 1' ];
push @{ $newhash{IP} }, [ 'row 1, col 0', 'row 1, col 1' ];

# $newhash{ IP } contains a reference to an array with two elements.
# Each element is itself a reference to an array with two elements. 
 
print $newhash{IP}->[0][0], "\n";    # row 0, col 0
print $newhash{IP}->[0][1], "\n";    # row 0, col 1
print $newhash{IP}->[1][0], "\n";    # row 1, col 0
print $newhash{IP}->[1][1], "\n";    # row 1, col 1