In last 15 years, I have 4+ years of experience in NOC 7312 (Heavy Duty Equipment Mechanic) and recent 4+ years in NOC 1225 (Purchasing Agents and Officer). In between I did Masters and traveling. I am an applicant of SNIP and I did Masters in Engineering. I have created my EE and SNIP profile considering NOC 7312 which was a mistake. Can I change it now? However, does NOC 1225 require any certification?