Actually, the default value of the fifth argument i.e. number of bits is 64, hence if we will not specify any value on fifth argument them MySQL will check the bits up to 64 bits and produce the result. It can be understood from the following example −
Example
mysql> SELECT EXPORT_SET(5, 'Y','N',' ')\G *************************** 1. row *************************** EXPORT_SET(5, 'Y','N',' '): Y N Y N N N N N N N N N N N N N N N N N N N N N N N N N N N N N N N N N N N N N N N N N N N N N N N N N N N N N N N N N N N N N 1 row in set (0.00 sec)
Here in this example, MySQL checked up to 64 bits and we use the space as separator.