Dear Aspirants ,

Yes it is valid and NIOS (National institute of open schooling ) is the board of education under the Union Government of India. It was established by the Ministry of Human Resource Development of the Government of Indian 1989 to provide education to all segments of society under the motive to increase literacy and aimed forward for flexible learning. The NIOS is a national board that administers examinations for Secondary and Senior Secondary examinations similar to the cbse board .So dont worry about the it is valid or not .

Hope it will hwlpful

Thanks