how to remove string?

[Richard]

Code:

EXPORT LIST_1:={1,2,3}; 
EXPORT LIST_2:={"A","B","C"};

ID;
NUMBER;
VAR;

EXPORT global2()
BEGIN

NUMBER:=1;
ID:=EXPR("'LIST_"+NUMBER+"'");  // ID  =LIST_1
VAR:=EXPR("'LIST_"+NUMBER+"'"); // VAR =LIST_1

LIST_2▶VAR;

PRINT;
PRINT(ID+"=");
PRINT(VAR);

END;

another example
Why can not the global variables be modified from the program?