#!/usr/bin/perl
use warnings;
use strict;
my %HoH;
my $value = "I have a value!";
my $G_Boardno = "curiosity";
my $G_ExcepId = "killed_the";
my $G_CauseCode = "cat";

$HoH{"$G_Boardno"}{"$G_ExcepId"}{$G_CauseCode}="$value";
print "My hash = ", $HoH{curiosity}{killed_the}{cat}, "\n";