The Usage section includes the following bullet regarding the NULL string:
If the start position or the length is negative, a NULL string is returned. If the start position is zero or longer than expr1, a NULL string is returned. If the length to be deleted is longer than expr1, expr1 is deleted through its last character (see Example 1).
Replace the original bullet with the following more accurate description:
If the start position or the length is negative, a NULL string is returned. If the start position is zero or longer than expr1, a NULL string is returned. If the length to be deleted is longer than expr1, expr1 is deleted through its last character (see Example 1).
