How to create colorimetric right shadows

As you know I give you before mont some ways for creating some an opening stage prepress in Xara - Vectors in one layer (exported like CMX or EPS on final), Rasters (incl. shadows, bevels, transperencies) in other exported like CMYK Tiff on final

now is time for tips & tricks about colorimetric correct shadows....

for example
create one shape in RED (100M/100Y)
over shape create some other shape - white for example and create it shadow.
If you remain shadow whit it def black, after export like CMYK Tif the shadow will be separated in all CMYK channels.
The decision is just to select only shadow and give it from color line black.
after export, shadow will be printed only in black chanell without perforating of Magenta and Yellow chanells

If you create some other color of shadow (for example magenta shadow over cyan shape used for background) then you must give it overprint fill - this will simulate transperency of magenta shadow over Cyan which color will be some over violet and will be exact exported from Xara to CMYK Tiff

That is it
simple like haricot beans ;)

The problem with shadows is a CMYK problem, because it is easy to say the shadow is black and it knocks the color out of the other channels. If the shadow is to be believed in CMYK, the percentages of the CMY do not change, the addition of the Black channel, creates the depth, and then it can be from 5 to 100 percent, in which case you have a saturated black.

my opinion is that when we have some background under shadow corect way is to create shadow just from black with multiply

but when is just white paper and shadow, if shadow is just from black she will look someway unreal, then the decision is to be comlex and printed in CMY or CMYK (using default settings for shadow) but in this case has risk to recieve yellowish, or bluish or redish toned shadow if color balance on offset machine is not reached well....