Character Set and Collation of Function Results +--------------------------------+ 1 row in set (0.00 sec) •For the  .  operator, the Spencer library matches line-terminator characters (carriage return, newline) anywhere in string expressions, including in the middle. To match line terminator characters in the middle of strings with ICU, specify the  m  match-control character. •The Spencer library supports word-beginning and word-end boundary markers ( [[:<:]]  and  [[:>:]] notation). ICU does not. For ICU, you can use  \b  to match word boundaries; double the backslash because MySQL interprets it as the escape character within strings. •The Spencer library supports collating element bracket expressions ( [.characters.]  notation). ICU does not. •For repetition counts ( {n}  and  {m,n}  notation), the Spencer library has a maximum of 255. ICU has no such limit, although the maximum number of match engine steps can be limited by setting the regexp_time_limit  system variable. •ICU interprets parentheses as metacharacters. To specify a literal open or close parenthesis  (  in a regular expression, it must be escaped: mysql>  SELECT REGEXP_LIKE(’(’, ’(’); ERROR 3692 (HY000): Mismatched parenthesis in regular expression. mysql>  SELECT REGEXP_LIKE(’(’, ’\\(’); +-------------------------+ | REGEXP_LIKE(’(’, ’\\(’) | +-------------------------+ | 1 | +-------------------------+ mysql>  SELECT REGEXP_LIKE(’)’, ’)’); ERROR 3692 (HY000): Mismatched parenthesis in regular expression. mysql>  SELECT REGEXP_LIKE(’)’, ’\\)’); +-------------------------+ | REGEXP_LIKE(’)’, ’\\)’) | +-------------------------+ | 1 | +-------------------------+ •ICU also interprets square brackets as metacharacters, but only the opening square bracket need be escaped to be used as a literal character: mysql>  SELECT REGEXP_LIKE(’[’, ’[’); ERROR 3696 (HY000): The regular expression contains an unclosed bracket expression. mysql>  SELECT REGEXP_LIKE(’[’, ’\\[’); +-------------------------+ | REGEXP_LIKE(’[’, ’\\[’) | +-------------------------+ | 1 | +-------------------------+ mysql>  SELECT REGEXP_LIKE(’]’, ’]’); +-----------------------+ | REGEXP_LIKE(’]’, ’]’) | +-----------------------+ | 1 | +-----------------------+ 12.8.3 Character Set and Collation of Function Results MySQL has many operators and functions that return a string. This section answers the question: What is the character set and collation of such a string? 2200