这些凹槽的作用是什么？
在椁板的两边，有一些凹槽，用以卡住几块椁板，以便于连接。[{'character': '在', 'pinyin': 'zai4', 'highest pitch': 10.08, 'lowest pitch': 8.57, 'duration': 0.3, 'prosody hierarchy': '#1'}, {'character': '椁', 'pinyin': 'guo2', 'highest pitch': 11.0, 'lowest pitch': 8.65, 'duration': 0.19, 'prosody hierarchy': 'null'}, {'character': '板', 'pinyin': 'ban3', 'highest pitch': 11.15, 'lowest pitch': 6.45, 'duration': 0.18, 'prosody hierarchy': 'null'}, {'character': '的', 'pinyin': 'de5', 'highest pitch': 7.57, 'lowest pitch': 6.63, 'duration': 0.07, 'prosody hierarchy': '#1'}, {'character': '两', 'pinyin': 'liang3', 'highest pitch': 8.28, 'lowest pitch': 4.48, 'duration': 0.25, 'prosody hierarchy': 'null'}, {'character': '边', 'pinyin': 'bian1', 'highest pitch': 9.61, 'lowest pitch': 7.84, 'duration': 0.29, 'prosody hierarchy': '#3'}, {'pinyin': 'sp1', 'highest pitch': 0.0, 'lowest pitch': 0.0, 'duration': 0.15}, {'character': '有', 'pinyin': 'iou3', 'highest pitch': 7.83, 'lowest pitch': 5.7, 'duration': 0.16, 'prosody hierarchy': 'null'}, {'character': '一', 'pinyin': 'i4', 'highest pitch': 5.91, 'lowest pitch': 5.49, 'duration': 0.1, 'prosody hierarchy': 'null'}, {'character': '些', 'pinyin': 'xie1', 'highest pitch': 12.34, 'lowest pitch': 5.85, 'duration': 0.16, 'prosody hierarchy': '#1'}, {'character': '凹', 'pinyin': 'ao1', 'highest pitch': 13.02, 'lowest pitch': 8.9, 'duration': 0.21, 'prosody hierarchy': 'null'}, {'character': '槽', 'pinyin': 'cao2', 'highest pitch': 9.68, 'lowest pitch': 5.69, 'duration': 0.41, 'prosody hierarchy': '#3'}, {'pinyin': 'sp1', 'highest pitch': 0.0, 'lowest pitch': 0.0, 'duration': 0.27}, {'character': '用', 'pinyin': 'iong4', 'highest pitch': 8.62, 'lowest pitch': 7.24, 'duration': 0.17, 'prosody hierarchy': 'null'}, {'character': '以', 'pinyin': 'i2', 'highest pitch': 7.98, 'lowest pitch': 7.13, 'duration': 0.14, 'prosody hierarchy': '#1'}, {'character': '卡', 'pinyin': 'qia3', 'highest pitch': 8.2, 'lowest pitch': 4.8, 'duration': 0.26, 'prosody hierarchy': 'null'}, {'character': '住', 'pinyin': 'zhu4', 'highest pitch': 7.57, 'lowest pitch': 6.36, 'duration': 0.17, 'prosody hierarchy': '#1'}, {'character': '几', 'pinyin': 'ji3', 'highest pitch': 6.36, 'lowest pitch': 4.68, 'duration': 0.14, 'prosody hierarchy': 'null'}, {'character': '块', 'pinyin': 'kuai4', 'highest pitch': 7.28, 'lowest pitch': 6.15, 'duration': 0.21, 'prosody hierarchy': '#1'}, {'character': '椁', 'pinyin': 'guo2', 'highest pitch': 11.0, 'lowest pitch': 6.3, 'duration': 0.22, 'prosody hierarchy': 'null'}, {'character': '板', 'pinyin': 'ban3', 'highest pitch': 11.15, 'lowest pitch': 4.38, 'duration': 0.34, 'prosody hierarchy': '#2'}, {'pinyin': 'sp1', 'highest pitch': 0.0, 'lowest pitch': 0.0, 'duration': 0.05}, {'character': '以', 'pinyin': 'i3', 'highest pitch': 7.2, 'lowest pitch': 6.75, 'duration': 0.16, 'prosody hierarchy': 'null'}, {'character': '便', 'pinyin': 'bian4', 'highest pitch': 8.79, 'lowest pitch': 7.5, 'duration': 0.18, 'prosody hierarchy': 'null'}, {'character': '于', 'pinyin': 'v2', 'highest pitch': 8.44, 'lowest pitch': 7.0, 'duration': 0.12, 'prosody hierarchy': '#1'}, {'character': '连', 'pinyin': 'lian2', 'highest pitch': 8.44, 'lowest pitch': 5.98, 'duration': 0.26, 'prosody hierarchy': 'null'}, {'character': '接', 'pinyin': 'jie1', 'highest pitch': 9.46, 'lowest pitch': 6.9, 'duration': 0.31, 'prosody hierarchy': '#4'}]