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

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

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

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

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