The General AAS category is a sort of catchall for a wide range of subjects. As well as textbooks for A and AS certification, it also includes things like study guides for the GCSE and UK Citizenship test.
Subjects covered will not only consist of standard core areas like Literature and Maths, but also Professional and Vocational revision guides and Exam preparation workbooks. Topics can be as diverse as programming and air traffic control, to name but a few.