Considerations on some neglected but impotant issues concerning the In
  ternal Linear Combination method in Astronomy
  Although the ``internal linear'' combination method (ILC) is a technique
widely used for the separation of the Cosmic Microwave Background signal from
the Galactic foregrounds, its characteristics are not yet well defined. This
can lead to misleading conclusions about the actual potentialities and limits
of such approach in real applications. Here we discuss briefly some facts about
ILC that to our knowledge are not fully worked out in literature and yet have
deep effects in the interpretation of the results.
