Spot colors are defined as extra print channels / extra inks. This is the definition and the most common use (precise terminology: spot colors used as process colors). Next to this spot colors are often used to name a color (precise terminology: named colors). The PDF model does not have a distinction between them and considers all spot colors as process colors so that areas that are covered with 2 or more (spot) colors are showing the correct overprint. This can be seen in the production preview of Adobe Acrobat.
The maximum number of channels/process colors allowed in a file is 32, this is including process colors, spot colors and special inks. If the number of channels goes above 32 some spots will be converted to process colors to ensure no more than 32 channels are used. To convert spot colors to process colors in Editor (E.g. Pantone 144 C to CMYK) then click the convert spot colors to process colors button highlighted below in the Output palette:
When the user wants to add the spot colors from the file to the ‘document color list’ then check the option “Convert Spot Colors to Defined Output Colors” option when using Open+ in Editor
If you choose this option, you will need to drag the spot colors from the color list to the output palette if you wish them to be defined as the original spot colors again.