This is merely because the guy who came up with the "left facing slash through the A (it also is NOT a serif) being only on early knives" doesn't know what he is talking about. Anybody can write a book, it doesn't mean that they got all the facts right. Advanced Case collectors know that the tested xx mark on pocket knives did not end in 1940 yet most people still accept this as gospel. I have proof that the Olcut mark by Union Cut is not pre KA-BAR, but ran concurrent with KA-BAR. Facts come to light after old books were written. The guy who wrote that business about the Marble's A was just plain incorrect.