This is a new category in my blog which includes some practical issues in using SAS. Even though I use SAS for many years, I still can't say I totally understand SAS. The depth of SAS programming is far away from what we can imagine. The powerful of SAS is absolutely, but the complication of it also troubles many users. Many Taiwanese students in UNC-CH often ask some SAS problems. I'd be glade to help them because they also give me the chance to face some challenges that I didn't encounter before. I am sincere to share my solutions in this blog. It is a sort of record, but I rather regard it as a cumulative experience of using SAS in my life.