The activities of the QCD working group concentrated on improving the
understanding and Monte Carlo simulation of multi-jet final states due to hard
QCD processes at LEP, i.e. quark-antiquark plus multi-gluon and/or secondary
quark production, with particular emphasis on four-jet final states and b-quark
mass effects. Specific topics covered are: relevant developments in the main
event generators PYTHIA, HERWIG and ARIADNE; the new multi-jet generator
APACIC++; description and tuning of inclusive (all-flavour) jet rates; quark
mass effects in the three- and four-jet rates; mass, higher-order and
hadronization effects in four-jet angular and shape distributions; b-quark
fragmentation and gluon splitting into b-quarks.Comment: 95 pages, 48 figures, contribution to Proceedings of the LEP2 Monte
Carlo Workshop. References for NLO 4-jet matrix elements adde
