  The precise determination of the Z boson parameters from the measurements at
the Z resonance by the four collaborations ALEPH,
  DELPHI, L3 and OPAL in e+e- collisions at the large electron positron
collider LEP at CERN is a landmark for precision tests of the electroweak
theory. The four experiments measured quantities which were used to extract the
mass and width of the Z boson, the hadronic cross-section at the pole of the
resonance, the ratio of hadronic and leptonic decay widths, and the leptonic
forward-backward asymmetries at the pole. The combination procedure based on
these parameters is presented in this paper.
