8Tang M, Wen Y, Mi X F, et al. Parametric modeling with user-defined features [C] //Proceedings of the 6th International Conference on Computer Supported Cooperative Work in Design, London, 2001:207-211.
9Hoffmann C M, Joan-Arinyo R. On user-defined features [J]. Computer-Aided Design, 1998, 30(5): 321-332.
10Choi G H, Mun D, Han S. Exchange of CAD part models based on the macro-parametric approach [J]. International Journal of CAD/CAM, 2002, 2(1): 23-31.
