XSharp

Identifiers in X# appear on many places in the language. They consist of a character followed by one or more characters, numbers or digits. The lexer definition for identifiers is below. As you can see we also allow 'special characters' and 'unicode characters' , but in general that is not recommended.
 

New keywords that are introduced in Vulcan and X# (see the keyword table) can also be used as Identifier

When an identifier must be used that has the same value as a keyword, then you can prefix the identifier with a double @@ sign, like in the following example.

This is not recommended. But it can happen that code in an external DLL has properties or method names that are keywords in X#. In that case using the @@ prefix can work too.

LOCAL @@Class as STRING
LOCAL @@Local as LOGIC

ID                        : IDStartChar IDChar*
                       ;
 
fragment IDStartChar: 'A'..'Z' | 'a'..'z'
                       | '_'
                       | '\u00C0'..'\u00D6'
                       | '\u00D8'..'\u00F6'
                       | '\u00F8'..'\u02FF'
                       | '\u0370'..'\u037D'
                       | '\u037F'..'\u1FFF'
                       | '\u200C'..'\u200D'
                       ;
 
fragment IDChar          : IDStartChar
                       | '0'..'9'
                       | '\u00B7'
                       | '\u0300'..'\u036F'
                       | '\u203F'..'\u2040'
                       ;