Hello aspirant,

School Leaving Certificate is the proof that you have left that school on account of various reasons - viz, Passed the Course, Further education is not available in that school, you have failed and do not want to pursue further education / education in that school or you would like continue education / further education in some other school. Such SLC is issued by the actual School where you pursued the education and not by Universities. School Leaving Certificate can also be used as proof of date of birth. SLC is issued in single copy. Off course, you can avail and obtain Duplicate copy / copies by furnishing application and affidavit at the every instance of such requirement. So its class 10 that they are asking for.

Hope it helped