The substr native AI script function returns a substring of the input string.

(substring: s)substr(string: s, start: f, length: f)

• string (string): The input string.
• start (float): The index of the first character to copy.
• length (float): The length of the returned substring.

• substring (string): A substring of the input string starting at character start and length characters long.

($str)result = substr("Hello, world!", 7, 5);

This example code returns the substring "world".