If a regular knife user of the mid 1960's would find nothing out of the ordinary about the design, then it's traditional.
That means large Buck 110-ish lockbacks are in.
SAKs date to the late 1800's. If they are not one hand opening, they are in. (See comments on materials of construction.)
Modern locking mechanisms such as Walker liner locks, pocket clips, holes / studs to allow one hand opening are all out. (Traditional liner locks, such as the lock on a TL29, are in.) Add a clip to a stockman, and it needs to be posted elsewhere. By the same token, if it is traditional except for a clip and you remove the clip, feel free to post it here.
We tend to have some tolerance when it comes to fixed blades. But, new designs with features such as glass breakers, are not included in this forum.
We give leeway on materials of construction. So if you have a nice stockman with G10 covers, it's traditional enough for us. After all, plastics have been used on knife handles since the 1800's. Stainless steel has been used in cutlery since the 1920's, so stainless is considered traditional. And even though PM alloys are new developments, that fella in the mid-1960's would never know the difference if he were looking at the knife, so they are OK, too.