frame top rail的用法和样例：
- Something, such as the top rail of a fence, that rests on or is supported by something else.
- For the diameters ratios, the stanchions pipe to ball is approx 0.6, top rail to ball is approx 0.5, mid rail to ball is approx 0.4.
- As they drove up by the ruins of the house, they saw Beatrice Tarleton dressed in a worn riding habit, a crop under her arm, sitting on the top rail of the fence about the paddock, staring moodily at nothing.
赶车经过住宅的废墟时，她们看见比阿特里斯 - 塔尔顿穿着破骑马服，臂下夹着一条马鞭，坐在牧场周围的篱笆顶上，一双忧郁的眼睛茫然地凝望着前方。
- C6MCC Maintenance of civil engineering Projects erected scaffolds where employees are working/passing below shall have planking or netting installed from the platform to the top rail.
- the top rail of a fence or balustrade.