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I found one that looks like yours, but the S is different and there are no dots.
The blade is pretty good. The dots are a dating system for Case, but I have not been able to find any with that pattern of 3 dots on the left and 4 on the right.
I found out that the "XX" on the tang of your knife stands for "eXX-changer" which refers to the fact that the blades are exchangeable. There are 3 different blades: yours, a sawtooth, and a saw. It also answers Fred's observation about the distressed look of the case vs the pristine look of the blade. Obviously yours is not a brand-new knife.
To verify or obtain more info Case Knife Co. is in business, located in Pennsylvania. They have a website.
Thank Tom. I contacted the Case Co. Waiting for a reply.