Special characters, except for the underscore, are not allowed. SAS reserves a few names for automatic variables and variable lists, SAS data sets, and librefs. The rules for SAS variable names have expanded to provide more functionality. SAS variable names may be up to 32 characters in length. The first character must begin with an alphabetic character or an underscore.
Subsequent characters can be alphabetic characters, numeric digits, or underscores.
A variable name may not contain blanks. A variable name may not contain any special characters other than the underscore. A variable name may contain mixed case. The mixed case is remembered and used for presentation purposes only. When SAS processes variable names, however, it internally uppercases them.