Bert for token classification BERT Tagging Inside–outside–beginning (tagging) : The IOB (short for inside, outside, beginning) is a common tagging format for tagging tokens. I- prefix before a tag indicates that the tag is inside a chunk. B- prefix before a tag indicates that the tag is the beginning of a chunk. An O tag indicates that a token belongs to no chunk (outside). Tagging: geo = Geographical Entity org = Organization per = Person gpe = Geopolitical Entity tim = Time indicator art = Artifact eve = Event nat = Natural Phenomenon