Books in this subject area deal with the Cambridge O Level, an internationally recognised qualification designed for 14 to 16 year-old students based on the traditional British GCE Ordinary Level qualification. It is part of the Cambridge Secondary 2 stage. A wide range of subjects are available in the Cambridge O Level curriculum, although some syllabuses such as Additional Mathematics and Computer Science are common with their IGCSE counterparts. All syllabuses in the Cambridge O Level curriculum are assessed on an 8-point scale of grades: One A* (A1), Two A (A2), Three B (B3), Four B (B4), Five C (C5), Six C (C6), Seven D (D7) and Eight E (E8), while "Ungraded" (U) indicates a standard below grade E8. Cambridge O Level is no longer listed on the examination timetables for administrative zones 1, 2 and 6, which includes North, Central and South America, and several of the Pacific Islands.