在C＃中没有多个定义的设计

I have a sample application and user control which uses separate copy of structure and enum. I want to know how to define this enum and structure, in order to use in my sample application as well as in my user control without having multiple definitions . i.e. only one copy of enum and structure should be present. If I do this code duplication can be avoided.I have a sample application and user control wh