A selection set can consist of a single object, or it can be a more complex grouping: for example, the set of objects on a certain layer. A selection set is typically created by requesting a user to select an object in the drawing area before a command is started through pick first selection or at the Select objects: prompt when a command is active.
选择集可以由单个对象组成，也可以是一个更复杂的编组：例如特定图层的对象集。 在命令启动前通过pick first选择或者执行命令后提示选择对象要注用户在图形区域中选择对象后创建的选择集是最具代表性的。
Selection sets are not persistent objects, if you need to maintain a selection set for use between multiple commands or future use, you will need to create a custom dictionary and record the object ids found in the selection set as a record.
选择集不是持久的，如果需要保留选择集，用于在多个命令之间或将来使用，就必须创建一个自定义的字典并记录对象 ID，并将选择集当作一个记录创建。
