Binary Logging and Contains SQL documentation

[Robert Hinks]

The documented behaviour for CONTAINS SQL is to indicate a routine neither reads nor writes data (http://dev.mysql.com/doc/refman/5.6/en/create-procedure.html). This suggests it is more restrictive than READS SQL DATA which is defined as indicating that a procedure can read but not modify data.

However, documented behaviour for binary logging is that CONTAINS SQL is not suitable and that NO SQL or READS SQL DATA must be used to indicate a function does not change data (http://dev.mysql.com/doc/refman/5.6/en/stored-programs-logging.html).

It is not clear from the name of the characteristic whether or not it can be used to read or modify data. If it is indeed more restrictive than READS SQL DATA why can READS SQL DATA be used with binary logging whereas CONTAINS SQL cannot?