Question: what is the full form of ms dos
[{'answer': 'Microsoft Disk Operating System', 'provenance': [{'wikipedia_id': '21291954', 'title': 'MS-DOS', 'start_paragraph_id': 1, 'start_character': 23, 'end_paragraph_id': 1, 'end_character': 54, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '21291954', 'title': 'MS-DOS', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 648, 'bleu_score': 0.897696685760027, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 11096725505897402034}, 'section': 'Section::::Abstract.'}]}]