/* For future work?  This does not preserve ID number of river so that
/* attributes can be transfered
NODEPOINT wholerivs allnodes
ae
 ec allnodes
 ef point
 sel flag = 'M'
 put mouths
 sel flag = 'S'
 put sources
quit
GRID
setwindow goodgrid ;setcell goodgrid
mouthg = pointgrid(mouths)
     &describe goodgrid
     setcell [calc %grd$dx% / 5]
     tmpr  = ^ isnull(LINEGRID(wholerivs))
     setcell maxof
     rivcount =  aggregate(tmpr ,5,sum,#,data)
     rgrid  = con(rivcount ge 3,1,mouthg ge 0,1)
/* replaced by code above   /* rgrid = LINEGRID(wholerivs)
setmask rgrid
  rid = costallocation(mouthg,rgrid,rivdist)
setmask off
/* because flowdir is suddenly flaky:
        rename rivdist uff
        rivdist = con(isnull(uff),1000000,uff)
        kill uff
/* end of flowdir fix
  rivdir = flowdirection(rivdist)
 orthoriv = streamline(rid,rivdir)
/* note: Douglas suggests setmask rgrid;griv = gridline(rgrid,#,nothin,#,#,#,5,#,#); setmask off, but I am not satisfied
QUIT
  ungenerate  POINT sources sources.gen
  &sys echo 'coord keyboard;clearsel;trace downstream orthoriv trueriv.sel # *' >! tmptrace.aml
  &sys sed 's/^ *[0-9]* */1,/' sources.gen | sed "s/1,END/[unquote '']/" >> tmptrace.aml
/* next line added 11/19/96
  &sys echo 9,0,0  >> tmptrace.aml
  &sys echo readselect trueriv.sel >> tmptrace.aml
  &sys /usr/bin/rm trueriv.sel
renode orthoriv  /* this is essential
ARCEDIT
  ec orthoriv
  ef arc
  sel all                /* this line added 11/19/96 
  arcplot tmptrace.aml
  selectget
  nsel
  delete
  sel all
  unsplit none
  save
quit
build orthoriv arc
GRID
setwindow goodgrid ;setcell goodgrid
thinrivs = linegrid(orthoriv)
spoofy = con(isnull(thinrivs),goodgrid,rivdist - 1000000)
&if [exist flowdir -grid] &then
  kill flowdir
flowdir = flowdirection(spoofy)
/* allflows = streamline(flowdir,flowdir)  /* diagnostic
flowacc = flowaccumulation(flowdir)

/* calcg = con(flowacc > 1000,1)
/* rawrcov = streamline(calcg,flowdir)
/* We have have two generated stream covers:
/*   orthoriv: a straightening of wholerivs
/*   calcg: based on flowaccumulation
/* What's the arcinfo equivalent of diff?
/* mainrcov = streamline(rgrid,flowdir)
/* arcedit
/*  FIND the arcs that are no coincident.
/*  INTERSECT and eliminate short dangles
/*  FIND dangles, use near to establish a path to river.
/*