In Vim, what characters are allowed in identifiers, such as variable names and function names?
I looked up the help for both variables and functions and neither one defines the allowable character set or syntax for valid identifiers.
*41.2* Variables A variable name consists of ASCII letters, digits and the underscore. It cannot start with a digit. Valid variable names are: counter _aap3 very_long_variable_name_with_underscores FuncLength LENGTH Invalid names are "foo+bar" and "6var".
And I think it's the same for functions, note that user defined functions must start with an uppercase letter (except from scriptlocal functions beginning with
s: as pointed out @D. Ben Knoble in the comments)