Naming conventions
Names of variables, categories and other elements of a variable, and filters must conform to the following rules:
1 The first character must be a letter or _ (underscore).
2 Subsequent characters can be:
▪letters
▪digits from either Basic Latin or other national languages
▪@, $, #, or _ symbols.
3 Embedded spaces and special characters are not allowed.
A letter is any English letter character (a-z, A-Z) or an alphabetical character from another language.
Reserved words
See also