MySQL can use slashes as field names

It was a surprise to find out today that MySQL can use slashes as field names.

 
CREATE TABLE `op_day` ( 
`id` int(11) NOT NULL AUTO_INCREMENT, 
`date` date NOT NULL DEFAULT '0000-00-00' COMMENT ' The date of ', 
`income` int(11) NOT NULL DEFAULT '0', 
`total` int(11) NOT NULL DEFAULT '0', 
`income/total` double(11,2) NOT NULL DEFAULT '0.00', 
PRIMARY KEY (`id`), 
KEY `unique` (`date`) 
) ENGINE=InnoDB AUTO_INCREMENT=0 DEFAULT CHARSET=utf8;