The IAB Taxonomy classifier categories texts into one of 360 topics. It has two levels of depth, a main category (e.g. sports, business or science) and subcategories (soccer, agriculture or physics). It's based on the IAB Quality Assurance Guidelines (QAG) Taxonomy. The class name has 4 parts, separated by underscores: "main topic_sub topic_id1_id2" where the ids are the IAB level 1 and 2 ids.