The General Certificate of Education (GCE) Ordinary Level, also called the O-level or O level, was a subject-based academic qualification. Introduced in 1951 as a replacement for the 16+ School Certificate (SC), the O-level would act as a pathway to the new, more in-depth and academically rigorous A-level (Advanced Level), in England, Wales and Northern Ireland. Later the complementary and more vocational Certificate of Secondary Education (CSE) was added to broaden the subjects available and offer qualifications in non-academic subjects.