NEED INFORMATION ABOUT CLASS IV COC UPGRADATION

Hello Friends
As per stcw 2010 all engineers officers have to do coc upgradation course.I have cleared class iv in july 2014 from kolkata. People who have cleared class iv in 2015 having only pssr according to stcw 2010 are getting coc valid upto 2020. As my coc is valid upto 2016.
MY question is if only refresher courses are done then class iv coc can be revalidated or still we...
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