{
 Special function codes.
}
    sf_def = 000010B; sf_gac = 002600B; sf_gmc = 002560B; sf_gsc = 002540B;
    sf_rdf = 002460B; sf_sac = 002620B; sf_smc = 002440B; sf_ssc = 002420B;
    sf_sts = 002520B; sf_stt = 002500B;