It is called adjacent-category logit model.
try link=alogit.
data data1;
set sashelp.class;
if _n_ lt 6 then levels='A';
else if _n_ lt 12 then levels='B';
else levels='C';
run;
proc logistic data=data1 descending;
class sex(ref='M') /param=ref;
model levels=weight age sex height /slstay=0.05 slentry=0.05
scale=none selection=stepwise aggregate link=alogit;
run;
OR if you don't have continuous variable, you could also try PROC CATMOD.
proc catmod.........
response alogit;
model......
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