Thank you so much for your reply.from what I have learnt it means you got nothing to worry about if you are indeed not a security risk or never involved in any activity that might endanger the security of this country .
I have been doing some research about all those checks , but I have no answer that tells clearly what all those checks exactly entail .
except security check, I did find this post , and I am quite satisfied with his answer . take a look and hope it will ease your mind , if you have no concern about your past .
Yes, I am not a threat to the security of Canada and I feel much relieved.