Question: what do rectangles with rounded corners in the bpmn model denote
[{'answer': 'activity', 'provenance': [{'wikipedia_id': '3015586', 'title': 'Business Process Model and Notation', 'start_paragraph_id': 4, 'start_character': 245, 'end_paragraph_id': 4, 'end_character': 253, 'bleu_score': 1.0, 'section': 'Section::::Overview.\n'}]}]