I always have assumed any screw that looked like a Phillips head was just that until I ran across this information regarding the JIS - Japanese Industrial Standard while reading the screwdriver notes in Cleaning the carbs 1 - Ninja250Wiki.
JIS screws may have a dot or "X" on the head to identify them. They are built to JIS 4633B-3/1991 and DIN/ISO standard 5260.
The Phillips head was invented by Henry Phillips in the 1930's to be used in assembly line production. Unlike the JIS drive, the Phillips drivers have an intentional angle on the flanks and rounded corners so they will cam out of the slot before a power tool will twist off the screw head.
The Phillips head tends to be fairly easy to strip particularly if the screw material or driver is soft or damaged. This was more of issue on motorcycles built in the 1960's but not so much anymore as Phillips/JIS screws have been replaced by hex head screws.
I was going to take a picture to show the difference between a Phillips and JIS screwdriver. There are subtle differences that don't show up well so I decided to just take a shot of the screwdrivers I got from
IKASWEBSHOP showing the No. 2, 1, 0 and 00 screwdrivers.
I originally ordered some German made screwdrivers from Ames Supply Company in Illinois online but they called me back and have a 50 dollar minimum order policy so I went with the Japanese Hozan's from IKASWEBSHOP in Everett. They have sort of chintzy handles but I'm assuming the steel is good and they'll work fine.
The Pozidriv® is another common type of screw that looks like a Phillips. These are sometimes called drywall or deck screws. They can be distinguished from Phillips by 4 indentations on the head as shown in this photo.
