Originally Posted by dsaul

The second example is a correctly oriented dropout slot for a disc brake fork. It prevents the rotational force from the disc rotor from ejecting the axle from the slot under braking. The first example is normal for non-disc forks and is apparently still being used because that's the way it was always done in the past. Its not inherently dangerous with a properly secured QR, but forward facing dropouts are safer.

By the way, I build forks and the term used by all parts manufacturers for the pictured part is "dropout". The slot orientation has nothing to do with the fork axle offset, which is erroneously referred to as "trail" by many in the cycling industry. .