This is a list of changes to pphtt.f since June 2000:

March 2 2006: - Typos in expressions for PT2SQ corrected
                (thanks to P. Gras)

April 12 2005: - Link to CTEQ6 and MRST2001 PDFs
                 (NGROUP = -1: CTEQ6    -2: MRST2001)

May 28 2003: - Change of the default scale choice to
               mu0 = (M_Higgs + 2*M_Q)/2

May 16 2002: - Addition of variable NQUARK to COMMON blocks
               (thanks to T. Trefzger)