if (levtype is "o2d" || levtype is "o3d") {
   alias mars.step = stepRange;
} else {
   alias mars.step = endStep;
}

if (class is "od" || class is "me" || class is "en" ||
    class is "c3" || class is "ci")
{
   alias mars.system = systemNumber;
}

alias mars.number = perturbationNumber;
alias mars.method = methodNumber;

if (class isnot "gw") { # ECC-1448
    alias mars.origin = centre;
}

# See ECC-624
if (centre == 80 && subCentre == 98 && (class is "c3" || class is "ci")) {
  constant cnmc_cmcc = 'cmcc';
  alias mars.origin = cnmc_cmcc;
}

if (class is "ci") { unalias mars.method; }