The arrival of the third decade of X-ray astronomy midway
through the ROSAT mission coincided with advances in CCD
detector technology that have allowed a vast increase in the
power of X-ray spectroscopy. These advances, coupled with
nested-mirror systems, mark a clear maturing in the field and a
move away from large samples of objects with limited information
to limited samples with very detailed information. This is an
inevitable progression that emerging disciplines experience,
radio astronomy being a prime example. With the advance of
aperture synthesis, radio astronomers in ~ 35 AJ (Anno Jansky)
could obtain insights into the nature of individual sources and
the focus moved away from surveys. In the past decade, radio
astronomy has turned back to surveys (NVSS, FIRST, WENSS,
4MASS), and this will happen in X-ray astronomy (but hopefully
in less than 25 years time!). This trend for more detailed study
has had a huge impact on cluster research, and the need for
spatially resolved spectroscopy of clusters w