  Underdoped high-Tc superconductors are frequently characterised by a
temperature, T*, below which the normal-state pseudogap opens. Two different
"phase diagrams" based on the doping (p) dependence of T* are currently
considered: one where T* falls to zero at a critical doping state and the other
where T* merges with Tc in the overdoped region. By examining the temperature
dependence of the NMR Knight shift and relaxation rate, entropy, resistivity,
infrared conductivity, Raman scattering, ARPES and tunnelling data it is
concluded that the second scenario is not at all supported. Neither can one
distinguish a small and a large pseudogap as is often done. T* is an energy
scale which falls abruptly to zero at p=0.19.
