I want to ask everyone how to protect the results of our design with corel draw format, so we design can only be opened in Corel and can not in foxes
It is hard to open a CorelDraw file in anything other than CorelDraw. To do so would require the programmer that created the other program to also create an import filter, which would be quite a substantial task.
However, anybody who has the CorelDraw program would be able to open the file and could therefore save it in another format that another program could open.
I'm not sure what you mean by "not in foxes". Firefox or Foxpro maybe? Neither of them are graphics design programs and neither will directly open a CorelDraw .CDR file.