As its name implies, a roll number slip is a number that the National Testing Service (NTS) of Pakistan issues to candidates that will serve to verify their eligibility to take the test. Candidates for an NTS-sponsored test are to take printouts of their NTS-issued roll number slips to NTS testing centers before taking the test.
The National Testing Service is an independent testing organization authorized by the Pakistani government to conduct national and international tests for its citizens. It was established in 2002 and it has since been authorized to conduct tests for school admissions, scholarships, recruitment, promotions and assessments. Among the tests that the NTS handles include Pakistan's National Aptitude Test, Graduate Assessment Test, Law Graduate Assessment Test and the Medical Representatives Certification Program.