Question: what does the r in hvacr systems refer to
[{'answer': 'Refrigeration', 'provenance': [{'wikipedia_id': '57169', 'title': 'Heating, ventilation, and air conditioning', 'start_paragraph_id': 1, 'start_character': 333, 'end_paragraph_id': 1, 'end_character': 346, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '57169', 'title': 'Heating, ventilation, and air conditioning', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 508, 'bleu_score': 0.9408228243926111, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 9148959677571264127}, 'section': 'Section::::Abstract.'}]}]