Anyone Recognize These Fasteners?

The bolts with the crown or dome heads are 7/16" dia and 1", 1 1/2", and 2" long. The 2" bolts have an integral washer under the head.

The standard bolts are 1/2" dia. and are 1 7/8" and 2 1/4" long.

The two oval heads are 1 1/2" x 2" with 1/2" studs about 1 1/4" long.

Any help in identifying what these are for would be appreciated.

The cap screws with the integral lock washer would be called "SEMS" screws, a proprietary method of securing the washer to the screw by a company called "Sems". They would be used to attach something like a bracket or other hardware to an assembly? or casting? where they thread into the parent part (not through it) when no nut is used to secure the bolt. *A lock washer is normally located between the nut and the object the bolt passes through, in this case they don't pass through the parent.

The "flat washer head" style screws are called "Elevator Bolts" where they would secure a flat floor wood sheet to an elevator cabin floor and be secured from beneath with a nut and washer. Purpose being the top floor would remain smooth and free of "bumps" when covered with linoleum or other flooring. They were used commonly on wood running board decking of early automobiles later covered by rubber matting.

There may be other specific uses I don't know about. Stude8