Compiling under Digital Unix

 f77  -o R.binary arithmetic.o array.o attrib.o bind.o builtin.o character.o coerce.o colors.o complex.o context.o cov.o cum.o debug.o deparse.o deriv.o devices.o dotcode.o dstruct.o duplicate.o envir.o errors.o eval.o format.o fourier.o iosupport.o gram.o list.o logic.o main.o match.o memory.o model.o names.o objects.o optimize.o options.o par.o paste.o plot.o plot3d.o plotmath.o print.o printarray.o printvector.o printutils.o random.o relop.o saveload.o scan.o seq.o sort.o source.o split.o subassign.o subscript.o subset.o summary.o unique.o util.o version.o ../lib/libgraphics.a ../lib/libunix.a ../lib/libappl.a ../lib/libmath.a -lSM -lICE -L/s/X11R6.3-1/lib -lX11 -ldnet_stub -ltermcap -lm 
 ld:
 ../lib/libunix.a(system.o): main: multiply defined
 fort: Severe: Failed while trying to link.

Is anyone familiar enough with Digital Unix to decide why it is
defining main in unix/system.o.  I checked and the symbol is indeed
defined there.