No Dan, for his purposes what I wrote is way more accurate than what you wrote. A 4x5 Graflex holder is too wide to fit in a Graflok/International back and the different light traps means that a 4x5 graphic type holder (sheet, roll film or grafmatic) won't seat properly in a graflex back since they don't have the extra slot that the 6x9 grafmatic has. The 4x5 holders simply aren't interchangeable. The link I provided shows the difference between the two types of grafmatics which will also be true for sheet film and roll film holders and also links to another page that shows both the graflex and graflok backs.