Why so many groups?
A major reason for dividing up the work in the IEC is to have certain committees responsible for the different types of EMC publication – Basic, Generic and Product standards. Some of these committees have broad-ranging horizontal functions while others have more product-oriented (or vertical) responsibilities.
Also, as we have seen, the term EMC is not restricted to the high-frequency region but applies to the whole spectrum of EM phenomena from 0 Hz to the GHz range. For practical as well as historical reasons the IEC has decided to divide the spectrum into low-frequency and high-frequency phenomena, setting a borderline at 9 kHz which is effectively the lower limit in the scope of CISPR's work.
This results largely from the different characteristics of the various phenomena and the specialized experience of experts working on EMC standardization in many technical committees both inside and outside the IEC.