lblfind BSET
( find word the same name as str in SI starting from tip in
  DI. Returns wordref in DI. Z if found, NZ if not. )
    CH CH XORrr, CL [SI] MOVr[], ( CX -> strlen )
    SI INCx, ( first char ) AX AX XORxx, ( initial prev )
    BEGIN, ( loop )
        DI AX SUBxx, ( jump to prev wordref )
        AL [DI] -1 MOVr[]+, ( strlen )
        CL AL CMPrr, IFZ, ( same len )
            SI PUSHx, DI PUSHx, CX PUSHx, ( --> lvl 3 )
            3 ADDALi, ( header ) AH AH XORrr, DI AX SUBxx,
            CLD, REPZ, CMPSB,
            CX POPx, DI POPx, SI POPx, ( <-- lvl 3 )
            IFZ, RETn, THEN,
        THEN,