function rdframe,lu,iprint=iprint
;
; Return a frame structure read from lu:
;
on_ioerror,badio
frsize = 0 & readu,lu,frsize
hdr1='' & hdr2='' & hdr3='' & hdr4=''
readu,lu,hdr1,hdr2,hdr3,hdr4
nx = 0 & xlab=''  & readu,lu,nx,xlab
xx = fltarr(nx)   & readu,lu,xx
ny = 0 & ylab=''  & readu,lu,ny,ylab
yy = fltarr(ny)   & readu,lu,yy
mtime = intarr(3) & readu,lu,mtime
f = fltarr(nx,ny) & readu,lu,f
;
; Define frame structure:
;
frame = {		$
  frsize:0,		$ frame size (currently dummy)
  hdr1:hdr1,		$ 1st header line
  hdr2:hdr2,		$ 2nd header line
  hdr3:hdr3,		$ 3rd header line
  hdr4:hdr4,		$ 4th header line
  nx:nx,		$ number of x coords
  xlab:xlab,		$ x-axis label
  xx:xx,		$ x coords
  ny:ny,		$ number of y coords
  ylab:ylab,		$ y-axis label
  yy:yy,		$ y coords
  mtime:mtime,		$ model time (day,hr,min)
  f:f			$ data
} 
;
if keyword_set(iprint) then begin
  print,format="(/72('-'))"
  print,strtrim(frame.hdr1)
  print,strtrim(frame.hdr2)
  print,strtrim(frame.hdr3)
  print,strtrim(frame.hdr4)
  print,'nx=',frame.nx,' xlab = ',strtrim(frame.xlab)
; print,'xx=' & print,frame.xx
  print,'xx=',frame.xx(0),' to ',frame.xx(nx-1),' by ',$
    frame.xx(1)-frame.xx(0) 
  print,'ny=',frame.ny,' ylab = ',strtrim(frame.ylab)
; print,'yy=' & print,frame.yy
  print,'yy=',frame.yy(0),' to ',frame.yy(ny-1),' by ',$
    frame.yy(1)-frame.yy(0)
  print,'mtime (day,hr,min)=',frame.mtime
  fmin = min(frame.f) & fmax = max(frame.f)
  print,' '
  print,'field min,max=',fmin,fmax
; print,'f=' & print,frame.f
  if iprint gt 1 then begin
frmin = {		$
  min:1.e36,		$
  ixmin:0,		$
  xmin:0.,		$
  iymin:0,		$
  ymin:0.		$
}
frmax = {		$
  max:-1.e36,		$
  ixmax:0,		$
  xmax:0.,		$
  iymax:0,		$
  ymax:0.		$
}
    for iy=0,ny-1 do $
        print,$
	format="('iy=',i3,' ny=',i3,' yy(iy)=',f9.2,' nx=',i3,' f(*,ny)=',/(6E12.4))", $
	iy,frame.ny,frame.yy(iy),frame.nx,frame.f(*,iy)

;pro frminmax, f,nx,xx,ny,yy,frmin,frmax,spval
    frminmax, frame.f,frame.nx,frame.xx,frame.ny,frame.yy,frmin,frmax,!spval
    print,'field min,max = ',frmin.min,frmax.max
    help,/struct,frmin
    help,/struct,frmax
  endif
  print,format="(72('-')/)"
endif
return,frame
badio: print,'>>> WARNING rdframe: i/o error on unit ',lu
lu = 0
return,0
end
;---------------------------------------------------------------
pro rdxdr
tgcmfile=''
read,'Enter xdr filename: ',tgcmfile
lu = 1
close,lu
openr,lu,tgcmfile,/xdr
nfr = 0
ans = ''
while (lu > 0) do begin
  frame = rdframe(lu)
  nfr = nfr+1
  print,'Read frame ',nfr
  contour,frame.f,frame.xx,frame.yy,/fol
  read,'Next frame? (y/n) ',ans
  if (ans ne 'y') then stop
end
return
end