When you create global colours from scratch, you can set these to be a spot colours.
About spot colours
In professional printing, spot colours can be used instead of CMYK process colours when your artwork contains a very limited colour set. By setting these colours to be spot colours, print costs can be reduced significantly. You may also be able to accurately reproduce colours otherwise impossible with process colours.
As well as setting a global colour to be a spot colour, you can use pre-supplied PANTONE® spot colours.
To create a spot colour:
On the Swatches panel, select a Document palette from the palette pop-up menu. If no Document palette exists you can create one from the panel's Panel Preferences menu.