Secondary Colour; Spot Colour - Oki OKIPAGE 8c Plus Colour Manual

Registration
This describes the alignment of the various colours when printing. As
each of the process primaries are specified by their own plate and printed
individually, it is important that the ink is placed in precise locations or
colours will not align to produce the desired result.
Saturation
This property indicates whether the colour will be perceived as dull or
vivid. A vibrant red is more saturated than brick red for example.

Secondary colour

Mixing two primary colours in equal amounts will produce a secondary
colour.

Spot colour

These are additional colours used in printing that are not a part of the
process ink set and specified individually. These colours are required
when the end result is of paramount importance (such as within a corporate
logo) as there is a substantial increase in cost. A separate plate is also
required.
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