imcombine ("@"//tmptmp, skyframe, sigma="", logfile=logfile,
    outtype="", option="median", expname=expname, exposure+,
    sca-, off-, wei+, modesec="", low=3., high=3., blank=-1)

imcombine ("@"//tmptmp, skyframe, plfile="", sigma="", logfile=logfile,
    combine="median", reject="none", project=no, outtype="", offsets="none",
    masktype="none", maskvalue=0.0, blank=-1.0, scale="exposure",
    zero="none", weight="exposure", statsec="", expname=expname,
    lthreshold=INDEF, hthreshold=INDEF, nlow=1, nhigh=1, mclip=yes,
    lsigma=3.0, hsigma=3.0, rdnoise="0.0", gain="1.0", sigscale=0.1,
    pclip=-0.5, grow=0)