Question: what does b mean on a number plate
[{'answer': 'Belgium', 'provenance': [{'wikipedia_id': '2035072', 'title': 'Vehicle registration plates of Europe', 'start_paragraph_id': 23, 'start_character': 12, 'end_paragraph_id': 23, 'end_character': 19, 'bleu_score': 1.0, 'section': 'Section::::Format.:European Union.\n'}]}]