Sorry if I confused everyone.
The attached picture is of some disassembled ST1100 forks (not my picture as I always have a good coating of fork oil all over me by this stage), 'helpfully' reversed side for side so the left antidive fork is on the right, and the right fork leg is on the left.
You can see the cartridge damper on the left, the skinny tube with a shaft leading up and out to the fork cap. Inside the tube is the moving rebound piston (on the end of the shaft) and at the bottom of the tube is the stationary compression piston. In this photo the bright silver piece on the lower end of the cartridge is the oil lock piece, which adds a hydraulic bumpstop as the fork tube end passes that point. Damping force is generated by flow through fix bleed orifices, and then by shim stacks being pushed off their seats at higher flow, which gives a linear response to suspension speed, allowing a controlled ride at low speeds, but the ability to smoothly soak up the faster hits without transferring too much jolting to the chassis. Cartridges are infinitely tunable with variables such as oil port size, bleed port size, shim configuration, and these can be different for rebound and compression because there is a separate valve for each function.
On the right is the damper rod fork, where the top end of the damper rod acts as a piston within the fork tube, compression damping is controlled by flow through the larger orifice and rebound damping is controlled by a smaller port and check valve at the lower extremity of the rod. All damping force is generated by oil flowing through the orifices in the rod, and this can be a compromise in that damping force increases with the square of the oil velocity. That means little or no damping (control) at low suspension speed, or too much at high speeds (approaching hydraulic lock), and a tough job finding the sweet spot. Cartridge emulators disable the compression damping function (by adding more holes to allow free flow) of the damper rod, and add a cartridge-like check valve and sprung shim to handle compression damping duties. The emulator just slips into the top of the rod and and is held in place by the main suspension spring.
On my bike I now have two cartridges, with one purchased off eBay replacing the damper rod in the left leg. I also have aftermarket valve bodies (Daugherty Motorsports) with custom shim stacks and stiffer straight-rate springs. If anyone wants my build recipe I am happy to share.
Disassembling the cartridges is pretty easy, just push the compression valve holder inwards to expose a small circlip, remove that and then the compression valve assembly will slide back out with just an o-ring seal for resistance. The rebound valve will slide right out of that end as well on the end of the damper shaft. The valves are simply held together by a socket head bolt (compression) and a 10mm nut on rebound, although the ends of the thread on the rebound valve are peened over and must be ground off to free the nut. And that's it, the shims will now slip off the valve assembly, but their sequence is important so don't mix the different thickness and diameters up.
The ST fork in my 1990 model was definitely biased towards comfort not control. The spring rates are not high, the compression damping is very light with a lot of free bleed and thin shims, and the rebound is similar but not as soft. This means it stays fairly soft and supple, but will also pogo and wallow when pushed harder. If you do most of your riding on smooth mostly straight roads, that is a good set up, but I don't live anywhere like that.