Spot color replacement.

Spot color replacement is the RIP intercepting a named color in the file, a PANTONE number or a brand's own swatch name, and printing a stored recipe for it instead of whatever the normal color conversion would have produced. The named-color libraries hold each color as a device-independent Lab value, and the RIP computes the best available reproduction for each output profile, recalculating the equivalents every time a profile is generated or updated. Treat that computed value as a starting point, not an answer: the recipe worth storing is the one you printed, measured with a spectrophotometer and entered back into the definition, because it is the only one that accounts for your ink film and what sits under it. Two traps follow. A replacement is bound to the output profile it was made against, so a brand red that lands on white cotton is quietly wrong on a heather blank; and a spot name that does not match the library exactly, one extra space or a lowercase suffix, matches nothing and passes through to a process build that nobody inspected before the run.