Thanks for your explanation Matt.
As I said before I've tried both variants of the Transform shader.
And the first time I've used the default shader to apply the image
as usual with objects and to my knowledge there is no scaling for
the colour image.
Furthermore I don't think the parts shader is splitable,so I'd have to
run the internal (inside the parts shader) shaders through several
transform merge shaders,which would be pretty cumbersome for an
object with let's say 30-100 different shaders.Especially when you
want to cover the whole object with some procedural texture,which
was my goal here.
Thank you,too,Kadri,I've done your experiments also,the day before
I posted image no.4.But originally it was about the default shader,
mind you.
Thanks again to all of you helping me to understand this better.