"Within the file system, the names have to be all lowercase" is not entirely true. I can create a file in both unix and widows at the operating system level where the name can be mixed case, all lower case, or all uppercase. Under unix I can create a file name that includes special characters and blanks (probably not a practice that is sympathetic to other users or unix command users!). It is just that SAS has some expectations about what the name of a file that is a SAS dataset should be called and perhaps what the case of the name is on disk. SAS / EG allows you to see two views of a dataset. One is the view of the dataset as a member of a SAS data library, and one as a view of the file in the file system. The library view presents all dataset names as uppercase, regardless of what their physical file name is on disk with extension sas7bdat. This is the same in SAS Studio under SAS Viya. The File view in SAS / EG shows the actual file name including the .sas7bdat extension. SAS / EG also uses the same dialogue of choices you can access from a right click on the object in either view. If you deliberately rename the dataset file name in the file view so that its name includes uppercase characters, then it becomes un-openable in SAS/EG. But this only happens if there is not a libname assigned to that same directory. Very particular I know, but a trap that can catch you if you are not careful. SAS dates from before the existence of either Windows or Unix. It has not become more relaxed and flexible in this area of naming objects as the operating systems have evolved to provide a better user experience.
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