这行impEx脚本的含义：$catalogVersion=catalogVersion(catalog(id[default=‘clothescatalog’]), version[default=‘Staged’])[unique=true,default=‘clothescatalog:Staged’]
Sets the default catalog to be clothescatalog:Staged, in total, and in parts (default=‘clothescatalog’ and default=‘Staged’, respectively). The following table visualizes what will happen if you give a value for the catalogVersion attribute using the above definition line and setting some values empty (n/a):
实际上就是给catalog和version指定了缺省值，如果用户指定了这两个字段的值，则用户指定值优先级更高，否则，用缺省值：
