alias mars.origin = centre;
alias mars.fcmonth = marsForecastMonth;
unalias mars.step;
alias mars.number = perturbationNumber;

alias mars.method = methodNumber;
if (class is "od") { alias mars.system = systemNumber; }
if (class is "c3") { alias mars.system = systemNumber; }

# 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; }