CMU申请时成绩单就必须WES认证吗

我们学校的成绩单是1000分制，CMU这样的要求“Institutions in the United States use Grade Point Average (GPA) on a 4.0 scale to record grades. If your institution reports grades in a different manner you may utilize the World Education Service (www.wes.org) to interpret your credentials for submission to our Graduate Admissions Committee. You must submit your GPA in the 4.0 scale to be considered for admission.“这句话怎么解释。是在考虑入学时再递交4.0的成绩单还是申请时就需要递交？