Question: what does aa on a license plate mean
[{'answer': 'cars of the royal family', 'provenance': [{'wikipedia_id': '2035072', 'title': 'Vehicle registration plates of Europe', 'start_paragraph_id': 38, 'start_character': 606, 'end_paragraph_id': 38, 'end_character': 630, 'bleu_score': 1.0, 'section': 'Section::::Format.:Common letter and digit systems between countries.\n'}]}, {'answer': 'reserved for cars of the royal family'}, {'provenance': [{'wikipedia_id': '2035072', 'title': 'Vehicle registration plates of Europe', 'start_paragraph_id': 38, 'start_character': 0, 'end_paragraph_id': 38, 'end_character': 919, 'bleu_score': 0.7443498485426601, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 2411263817734965242}, 'section': 'Section::::Format.:Common letter and digit systems between countries.\n'}]}, {'provenance': [{'wikipedia_id': '2035072', 'title': 'Vehicle registration plates of Europe', 'section': 'Section::::Format.:Common letter and digit systems between countries.\n', 'start_paragraph_id': 38, 'end_paragraph_id': 38, 'meta': {'evidence_span': ["BULLET::::- The Netherlands (until 2008) and Portugal both use three groups of two characters (letters or numbers) in several sequences: codice_1, codice_2, codice_3, codice_4, etc. However, Portuguese plates have a white background, while those of Netherlands (after 1 January 1978) have a yellow one, though both countries also use white letters on blue plates for classic cars. Furthermore, newer plates on Dutch vehicles only contain consonants, to avoid coincidental abbreviations or words. Also some sensitive letter combinations, such as SS or SD, are not used. The combination 'AA' is reserved for cars of the royal family. Dutch company registered bus, truck and/or minivan plates always start with a codice_5 or a codice_6. Dutch taxis use blue registration plates. The number of new combinations ran out in 2008. New registered cars in the Netherlands now use the format of two digits-three letters-one digit (codice_7).", 'cars of the royal family', "The combination 'AA' is reserved for cars of the royal family. Dutch company registered bus, truck and/or minivan plates always start with a codice_5 or a codice_6. Dutch taxis use blue registration plates. The number of new combinations ran out in 2008."]}}]}]