The generation semantics and engineering semantics of two and one half D features, the separation of adjacent features with different semantics and the composition of the features with the same semantic features are explained with samples.

• 结合实例介绍了二又二分之一维特徵的生成语义和加工语义，在特徵转换过程中不同语义邻接特徵的分离，以及相同语义特徵转换而成的加工特徵之间的结合。