NCC is an organisation called National Cadet Crops which is a youth organisation where young school and college students can join. The motto of NCC is unity and discipline. There is a seat reservation for the members of NCC in some colleges. To know about all the category codes, you can click on the following link:

http://www.cee-kerala.org/docs/keam2017/category/cat_desc.pdf

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NC OBC implies Non Creamy Layer candidates among the OBC candidates. As per the latest government regulations, any candidate belonging to the OBC category and having a family income less than 6lpa belong to the non creamy layer and are entitled to the benefits of reservation.