DS = "Design Samples"
DS are hand-made prototypes of our parts. Typically, they are only distributed to key customers with the caveat/disclaimer that they are in no way a "final" or "polished" version and are not to be used for reliability testing.
CS = "Champion Samples"
Depending on product type (resistor, LED, printhead, IC, etc.), release of CS usually occurs a few months after DS. Generally speaking, CS is considered to be the first production run of the part. Availability is limited, but production groups are usually more agreeable to the distribution of these parts on a slightly wider scale.
MP = "Mass Production"
At MP, the product specification is finalized, and generally speaking, parts are made available to the public at large (given lead time). Again, depending upon product type, there may be up to a few months between the CS stage and MP. During this time, "tweaks" are made to the production process in order to maximize yield, the spec is locked in, and ramp up begins.