[Rivet] HepMC 2.04.00.beta2

[Alberto Ribon]

  Hello,

  taking into account the feedbacks we got from the
  first beta release of HepMC 2.04.00, we have prepared
  a second one (that we hope will be the last before
  the official release):

    /afs/cern.ch/sw/lcg/external/HepMC/2.04.00.beta2

  For this beta release, only the library for the platform 
  slc4_amd64_gcc34  is available.

  The changes that have been made with respect to the
  first beta release are related only to units.

  The choices for the units are now the following:

    o  For Momentum : MEV and GEV
       (to be used in the code as: 
          HepMC::Units::MEV , HepMC::Units::GEV )

    o  For Length : MM and CM
       (to be used in the code as: 
          HepMC::Units::MM , HepMC::Units::CM )

  Notice that "UNKNOWN" has now been removed.

  The default units must be specified at configuration time,
  before compiling HepMC, for example:

       configure --with-momentum=MEV --with-length=MM ...

  This is actually the choice used to build the library
  on AFS, because it coincides with the default units of 
  both ATLAS and LHCb. 

  CMS and MC authors are used to build HepMC from source
  and therefore they can specify their preferred units at 
  configuration time, as shown above.

  Independently of the chosen default units, users are
  strongly adviced to explicitly specify the units when
  calling the constructor of GenEvent, for example:

  GenEvent* evt = new GenEvent( HepMC::Units::MEV, 
                                HepMC::Units::MM );


  For more details, see:

        http://lcgapp.cern.ch/project/simu/HepMC/20400/


  Please send your feedbacks to me and Lynn Garren
  possibly before  *** Wednesday 4 June *** .


  Best regards,
               Alberto