can be either user-defined characters, system-specific characters or third-party add-on products. Both are a problem for information interchange, as the code point used to represent an external character will not be consistent from one computer or operating system to another.
can be either user-defined characters system-specific characters or third-party add-on products both are a problem for information interchange as the code point used to represent an external character will not be consistent from one computer or operating system to another