Shock valving is a way of referring to the way the shock damps motion.
All a shock absorber does is slow down the motion gradually, instead of allowing the motion to jolt you.
Think of a catcher catching a 100 mph fast ball....
He does NOT just let the ball slam into his palm at 100 mph...it would break his hand (Jolt)....he pulls the glove back on impact, to allow the impact to be softened.
On a suspension....the perfect set up would mean your truck would stay dead level while your tires went up and down, following the terrain.
To allow the tires to go up and down, without the truck popping up or dipping down with the tires...the shocks have to be matched to both the SPEED and the WEIGHT of the motion.
If a tire is rising TOO FAST for the shock to compress with/or, the shock's RESISTANCE to compression is too much for the force involved...the truck is pushed UP on that corner.
If the tire is sinking too fast for the shock to extend with/or the FORCE of that motion is OVERWHELMING the shock's ability to resist it, the truck DIPS at that corner.
The AMOUNT of damping forces the shock can handle is represented by numbers that are referred to as the shock's VALVING.
Just like an RTI Ramp score, there are different scales used to rate that valving...but, generally, its in terms of Newtons (The FORCE) damped at a SPEED of 20" per second, or at 0.52 meters per second (metric version...).
To make it harder to understand, they THEN take THAT number, and DIVIDE it by TEN (10) to get the "Valving" number.
So, If I have a shock that is valved at 275/100...that means it damps 2,750 Newtons at 20"/sec on Rebound (Shaft Extending)
/1,000 Newtons at 20"/sec on Compression (Shaft going back into the shock body...)
Generally, for control purposes....the REBOUND valving helps to control the SPRUNG weight (Frame, etc...), and COMPRESSION valving helps to control the UNSPRUNG weight (Axles, tires, etc...).
So - the shock has to deal with the Pitch (Brake Dive/Wheelie Pop type motions...) and Yaw (Roll in turns/Leaning over type motions...) of the TRUCK, as well as the motions of the tires and axles, etc, going up and down with the terrain.
For example, we said that Compression helps to control the UNsprung weight (Tires, etc...)....
...If the Compression valving is set to too high a number, the tire will skate over small bumps, etc....as it won't let the tire rise for each one fast enough, etc.
If the Compression is at too low a number, the tire will bounce up too quickly, and overshoot the next bump, or wheel hop, etc.
So there's NO universal answer, as different rigs have different forces to control.
My 2.5 ton Rockwells represent an ENORMOUS unsprung weight compared to your D30 for example, the stock 32's are very light compared to someone else's 37's, and so forth...so, if I am running larger tires, heavier axles, or a STIFFER SUSPENSION, like with LIFT COILS or stiffer leaf packs, etc...the spring's forces, AND the weights of the unsprung components, ALL change my ideal COMPRESSION valving ranges.
If I am running a CJ5, or a Sammi, etc...I have very little SPRUNG weight compared to a JK UL or a Ford F350, etc....so, the shocks will have different ideal ranges of REBOUND as well.
If I have a different lift HEIGHT, I am changing my Center of Gravity (COG)...and, therefore, both my Pitch and Yaw characteristics...as the higher COG leans more, etc.
and so forth.
If two rigs are at least similar in sprung and unsprung weight, and use similar suspension coil rates, etc...then the shock valving ranges will be similar as well....but, even THAT is subject to OTHER variables...
...For example, some shocks are mounted more straight up and down, and, some are set at an angle.
Well, that changes the LEVERAGE that the sprung, and unsprung, weights can exert upon the shock, and the speeds at which they will act.
If I am picking up a plank of wood, and your job is to hold it down, would you rather hold it down standing off to the side so your arm is at a 45 degree angle, or standing so you are over the board with your arm straight down?
Well, same for the shock...the more of an angle off of straight, the less leverage it has.
If it has 1,000 Newtons of resistance to offer at a perpendicular angle, it may only have an equivalent 500 at a 45 degree angle, etc...
Which means, if one rig has the shock straight down to the axle, and the other has the shock at a 45 degree angle, the one at the 45 degree angle may need a much stiffer shock to control the same weight.
and so forth.
So - that's what the valving numbers are trying to tell you.
PS - Proprietary Valving simply means they don't list it, as, a lot of research went into figuring that out, and, they do NOT want to just GIVE all of that time and effort to a competitor/make it too easy for you to go to eshocks.com, etc...and order the same shock for less, etc...