FUNCTION ieeeopen, filename
   IF N_PARAMS() NE 1 THEN BEGIN
      print, 'open_ieee: Need filename'
      RETURN, 0                 ; undefined
   ENDIF

   openr, unit, filename, /GET_LUN
   print,unit
   finfo = fstat(unit)
   loninfo =  assoc(unit, lonarr(1))
   bytinfo =  assoc(unit, bytarr(1))
   IF 16909060 THEN BEGIN       ; thats the magic number
      print, 'open_ieee: This is not an IEEEIO file; ', filename
      RETURN, 0
   ENDIF
                                ; we'll switch to handles later for the
                                ; following data structure;
   descriptor = {IEEEINFO, NDATASETS:0, UNIT:0, DATASETS:LONARR(5000), ATTRIBUTES:LONARR(5000, 12)}
   descriptor.unit = unit
   descriptor.ndatasets = (loninfo(2))(0)

   PRINT, 'scanning file for records' ; now scan the file for records
   FINDEX = LONG(16)
   FOR I=0, descriptor.ndatasets-1 DO BEGIN
      PTR = assoc(unit, LONARR(1), FINDEX) ; 0=type<1 is data> 1=len 2=seq
      IF (PTR(0))(0) EQ 1 THEN BEGIN 
         descriptor.DATASETS(I) = FINDEX ; store this data offset 
                                ;print, 'Data RecordI=', i
                                ;print, 'RecordType=', PTR(0)
                                ;print, 'RecordLength=', PTR(1)
                                ;print, 'RecordSeq=', PTR(2)
         FINDEX = FINDEX + 12 + (PTR(1))(0) ; NOW Seek to the next record
         FOR J=0, 11 DO BEGIN
            PTR = assoc(unit, LONARR(1), FINDEX) ; 0=type<1 is data> 1=len 2=seq
                                ;print, 'I=', i, '  J=', j
                                ;print, 'RecordType=', PTR(0)
                                ;print, 'RecordLength=', PTR(1)
                                ;print, 'RecordSeq=', PTR(2)
            IF (PTR(0))(0) EQ 3 THEN descriptor.ATTRIBUTES(I,J) = FINDEX ; store annotation offset
            IF (PTR(0))(0) EQ 1 THEN J = 11 ELSE FINDEX = FINDEX + 12 + (PTR(1))(0)
            IF FINDEX GE finfo.size THEN J = 11 
         END
      ENDIF
   END
   print, 'was successful'
   RETURN, descriptor
END

PRO ieeeclose, descriptor
   IF descriptor.unit GE 0 THEN close, descriptor.unit ELSE print, 'closeieee: Already closed'
   descriptor.unit = -1
   print, 'closeieee: done'
   RETURN
END

FUNCTION ieeendatasets, descriptor
   IF N_PARAMS() LE 0 THEN BEGIN 
      print, 'PRO ieeendatasts: Requires an ieeeio file descriptor'
      RETURN, -1
   ENDIF
   IF descriptor.unit LT 0 THEN BEGIN 
      print, 'PRO ieeendatasts: error, descriptor is closed or invalid'
      RETURN, -1
   ENDIF
   RETURN, descriptor.ndatasets
END

FUNCTION ieeenattribs, descriptor, datasetnumber
   IF N_PARAMS() LT 2 THEN BEGIN 
      print, 'PRO ieeendatasts: Requires an ieeeio file descriptor and the dataset number.'
      RETURN, -1
   ENDIF
   IF descriptor.unit LT 0 THEN BEGIN 
      print, 'PRO ieeendatasts: error, descriptor is closed or invalid'
      RETURN, -1
   ENDIF
   IF datasetnumber GE descriptor.ndatasets THEN BEGIN
      print, 'PRO ieeenattribs: There are only ', descriptor.ndatasets, ' datasets in this file '
      print, '  You were requesting info from dataset number ', datasetnumber
      RETURN, -1
   ENDIF
   nattribs = 12 ; default
   FOR I=0, 11 DO BEGIN
      IF descriptor.attributes(datasetnumber, I) EQ 0 THEN BEGIN
         nattribs = I
         I = 11 ; exit the loop
      ENDIF
   END
   RETURN, nattribs
END

PRO ieeereadattr, descriptor, datasetnumber, NAME=name, NUMBER=attribnumber, LENGTH=len, TYPE=datatype, DATA=data, ASSOC_ELEMENTS=assoc_e, ASSOC_1D=assoc_1d, COPY=cpy, ALLOCATE=alloc, INFO=nodat, BYNAME=byname
   IF N_ELEMENTS(descriptor) LT 1 THEN BEGIN
      print, 'PRO ieeeread: You need to provide at least a IEEE file descriptor to call this routine'
      RETURN
   ENDIF
   IF descriptor.unit LT 0 THEN BEGIN
      print, 'PRO ieeeread: The IEEE file descriptor you specified is either closed or invalid'
      RETURN
   ENDIF
   IF N_ELEMENTS(datasetnumber) LT 1 THEN datasetnumber = 0 ; eg. default datasetnumber=0
   IF datasetnumber GT (1+descriptor.ndatasets) THEN BEGIN
      print, 'PRO ieeeread: There are only ', descriptor.ndatasets, ' datasets in this file'
      print, 'You attempted to read dataset number ', datasetnumber
      RETURN
   ENDIF
                                ; should check for indexing past max
                                ; annotation index
   IF (N_ELEMENTS(attribnumber) EQ 0) OR (KEYWORD_SET(BYNAME) NE 0) THEN BEGIN ; no index provided, so we are probably searching by name
                                ; print, 'Byname flag is set or NUMBER is not set'
      IF (KEYWORD_SET(NAME) NE 0) THEN BEGIN ; find attribute by name (ICK!)
                                ; lets call ourself recursively to
                                ; scan for attrib names
                                ; print, 'We are searching by name
                                ; because the number is undefined'
         nattribs = ieeenattribs(descriptor, datasetnumber)
         FOR i=0, nattribs-1 DO BEGIN ; for each annotation
                                ; use recursive call to get the name
                                ; of the parameter
            IF descriptor.attributes(datasetnumber, i) NE 0 THEN ieeereadattr, descriptor, datasetnumber, NUMBER=i, NAME=nm, /INFO
            IF nm EQ name THEN BEGIN 
               attribnumber = i
               i = nattribs-1           ; end the search
            ENDIF
         END
         IF nm NE name THEN BEGIN ; that name was not found
            attribnumber = -1
            len =  -1
            datatype = -1
            RETURN              ; would be easier if could return scalars from a PRO
         ENDIF
      ENDIF
   ENDIF
   IF KEYWORD_SET(assoc_e) THEN assoc_e = 1 ELSE assoc_e = 0 ; this is just for convenience (you'll see)
   IF KEYWORD_SET(assoc_1d) THEN assoc_1d = 1 ELSE assoc_1d = 0
   IF KEYWORD_SET(cpy) THEN cpy = 1 ELSE cpy = 0
   IF KEYWORD_SET(alloc) THEN alloc = 1 ELSE alloc = 0
   IF KEYWORD_SET(nodat) THEN nodat = 1 ELSE nodat = 0
   IF KEYWORD_SET(byname) THEN byname = 1 ELSE byname = 0
   
   ;print, 'lets read some info' ; Now lets read the info
   attribhdr = assoc(descriptor.unit, lonarr(1), descriptor.attributes(datasetnumber, attribnumber) + 12)
   len = (attribhdr(0))(0)
   datatype = (attribhdr(1))(0)
   namelen = (attribhdr(2))(0)
   namehdr =  assoc(descriptor.unit, bytarr(namelen-1), descriptor.attributes(datasetnumber, attribnumber) + 24) ; offset to stored name
   offset = descriptor.attributes(datasetnumber, attribnumber) + 24 + namelen ; used for data reading later on
   IF datatype EQ 1 THEN len = len / 2 ELSE $ ; the length is in bytes, must divide by sizeof type
     IF (datatype EQ 2) OR (datatype EQ 4) THEN len =  len / 4 ELSE $
     IF (datatype EQ 3) OR (datatype EQ 5) THEN len =  len / 8 ; default is BYTE
   
                                ;print, 'len=', len, ' type=', datatype, ' namelen=', namelen
                                ; note: the bytarr is of length
                                ;       namelen-1 to strip it of the
                                ;       null terminator
   bname = namehdr(0)
                                ; print, 'bname='
                                ;help, bname
   name = STRING(bname)         ; convert from bytarr to String type
                                ; print, 'name=', name

   IF nodat NE 0 THEN RETURN    ; we've copied all of the info and they don't want the data so...
   print, 'now well read some data'
   CASE datatype OF
      0:BEGIN
         IF assoc_e THEN data = assoc(descriptor.unit,bytarr(1), offset) ELSE $
           IF assoc_1d THEN data = assoc(descriptor.unit,bytarr(len), offset) ELSE BEGIN
                                ; Associate with file descriptor since
                                ; this is the only simple way to lseek() in IDL; 
            rawdata = assoc(descriptor.unit, bytarr(len), offset)
                                ; Here's where we actually assign or
                                ; copy the data
            IF (N_ELEMENTS(data) NE len) OR (alloc NE 0) THEN data = rawdata(0) ELSE data(*) =  rawdata(0) ; copy 1D
         ENDELSE
      END
      1:BEGIN
         IF assoc_e THEN data = assoc(descriptor.unit,intarr(1), offset) ELSE $
           IF assoc_1d THEN data = assoc(descriptor.unit,intarr(len), offset) ELSE BEGIN
                                ; Associate with file descriptor since
                                ; this is the only simple way to lseek() in IDL; 
            rawdata = assoc(descriptor.unit, intarr(len), offset)
                                ; Here's where we actually assign or
                                ; copy the data
            IF (N_ELEMENTS(data) NE len) OR (alloc NE 0) THEN data = rawdata(0) ELSE data(*) =  rawdata(0) ; copy 1D
         ENDELSE
      END
      2:BEGIN
         IF assoc_e THEN data = assoc(descriptor.unit,lonarr(1), offset) ELSE $
           IF assoc_1d THEN data = assoc(descriptor.unit,lonarr(len), offset) ELSE BEGIN
                                ; Associate with file descriptor since
                                ; this is the only simple way to lseek() in IDL; 
            rawdata = assoc(descriptor.unit, lonarr(len), offset)
                                ; Here's where we actually assign or
                                ; copy the data
            IF (N_ELEMENTS(data) NE len) OR (alloc NE 0) THEN data = rawdata(0) ELSE data(*) =  rawdata(0) ; copy 1D
         ENDELSE
      END
      3:BEGIN
         print, 'PRO ieeeread: Error... This data is Int64 and IDL has no 64-bit integer datatype.'
      END
      4:BEGIN
         IF assoc_e THEN data = assoc(descriptor.unit,fltarr(1), offset) ELSE $
           IF assoc_1d THEN data = assoc(descriptor.unit,fltarr(len), offset) ELSE BEGIN
                                ; Associate with file descriptor since
                                ; this is the only simple way to lseek() in IDL; 
            rawdata = assoc(descriptor.unit, fltarr(len), offset)
                                ; Here's where we actually assign or
                                ; copy the data
            IF (N_ELEMENTS(data) NE len) OR (alloc NE 0) THEN data = rawdata(0) ELSE data(*) =  rawdata(0) ; copy 1D
         ENDELSE
      END
      5:BEGIN
         IF assoc_e THEN data = assoc(descriptor.unit,dblarr(1), offset) ELSE $
           IF assoc_1d THEN data = assoc(descriptor.unit,dblarr(len), offset) ELSE BEGIN
                                ; Associate with file descriptor since
                                ; this is the only simple way to lseek() in IDL; 
            rawdata = assoc(descriptor.unit, dblarr(len), offset)
                                ; Here's where we actually assign or
                                ; copy the data
            IF (N_ELEMENTS(data) NE len) OR (alloc NE 0) THEN data = rawdata(0) ELSE data(*) = rawdata(0) ; copy 1D
         ENDELSE
      END
   ENDCASE
   RETURN
END

PRO ieeeread, descriptor, datasetnumber, RANK=rank, DIMENSIONS=dims, TYPE=datatype, DATA=data, ASSOC_ELEMENTS=assoc_e, ASSOC_1D=assoc_1d, COPY=cpy, ALLOCATE=alloc, INFO=nodat

   IF N_ELEMENTS(descriptor) LT 1 THEN BEGIN
      print, 'PRO ieeeread: You need to provide at least a IEEE file descriptor to call this routine'
      RETURN
   ENDIF
   IF descriptor.unit LT 0 THEN BEGIN
      print, 'PRO ieeeread: The IEEE file descriptor you specified is either closed or invalid'
      RETURN
   ENDIF
   IF N_ELEMENTS(datasetnumber) LT 1 THEN datasetnumber = 0 ; eg. default datasetnumber=0
   IF datasetnumber GT (1+descriptor.ndatasets) THEN BEGIN
      print, 'PRO ieeeread: There are only ', descriptor.ndatasets, ' datasets in this file'
      print, 'You attempted to read dataset number ', datasetnumber
      RETURN
   ENDIF
   IF KEYWORD_SET(assoc_e) THEN assoc_e = 1 ELSE assoc_e = 0 ; this is just for convenience (you'll see)
   IF KEYWORD_SET(assoc_1d) THEN assoc_1d = 1 ELSE assoc_1d = 0
   IF KEYWORD_SET(assoc_2d) THEN assoc_2d = 1 ELSE assoc_2d = 0
   IF KEYWORD_SET(assoc_3d) THEN assoc_3d = 1 ELSE assoc_3d = 0
   IF KEYWORD_SET(cpy) THEN cpy = 1 ELSE cpy = 0
   IF KEYWORD_SET(alloc) THEN alloc = 1 ELSE alloc = 0
   IF KEYWORD_SET(nodat) THEN nodat = 1 ELSE nodat = 0

   datahdr = assoc(descriptor.unit, lonarr(1), descriptor.datasets(datasetnumber) + 12)
                                ; datasize,numbertype,rank,dims(ndims)
   datatype = (datahdr(1))(0)
   rank = (datahdr(2))(0)
   IF n_elements(dims) LT rank THEN dims = intarr(rank)
   FOR I=0, rank-1 DO dims(I) = (datahdr(3+I))(0) ; copy the dims
   print, 'dims=', dims

   offset = descriptor.datasets(datasetnumber) + 24 + rank*4
   unit = descriptor.unit
                                ; In this section we do sanity checks
                                ; on the calling parameters
   aflags = assoc_e + assoc_1d + assoc_2d + assoc_3d
   print, 'aflags=', aflags
   IF aflags GT 1 THEN print, 'PRO ieeeread: you can only use one association type... not ALL of them'
   dflags = cpy + alloc + nodat
   print, 'dflags=', dflags
   IF dflags GT 1 THEN print, 'PRO ieeeread: Choose one of /COPY, /ALLOCATE, or /INFO.'
   IF (dflags GT 1) AND (aflags GT 1) THEN print, 'PRO ieeeread: the /ASSOC flags are mutually exclusive of all of the others.  Dont mix them'
   IF (nodat) THEN BEGIN        ; IF (nodat) OR (KEYWORD_SET(DATA) EQ 0) THEN BEGIN
                                ; GRRRR.... if data is empty, then
                                ; keyword_set(DATA) gives 0.  There is
                                ; way to see if someone said "DATA=d"
                                ; at the call.  So, must force people
                                ; to use /INFO switch to tell if they
                                ; don't intend to read any data.
                                ;print, 'DATA Keyword val=', KEYWORD_SET(DATA)
      RETURN                    ; no data or (eg. the /INFO flag)
   ENDIF
   nelements = LONG(1)
   FOR I=0,rank-1 DO nelements = nelements*dims(I)
   print, 'nelements=', nelements
   IF (cpy) THEN BEGIN
      IF (N_ELEMENTS(DATA) LT nelements) THEN BEGIN
         print, 'PRO ieeereader: The dataset requires ', nelements, ' you have only provided ', N_ELEMENTS(DATA)
         print, ' If you want this routine to do the allocation, then use /ALLOCATE or dont use the /COPY flag'
         print, ' Otherwise you should allocate data of the proper type and size for reading'
         print, ' Dimensions are not important as long as you have enough elements'
         RETURN
      ENDIF
                                ; will have additional checks for
                                ; datatype sanity here
   ENDIF
   print, 'now we read data'
   CASE datatype OF
      0:BEGIN
         IF assoc_e THEN data = assoc(descriptor.unit,bytarr(1), offset) ELSE $
           IF assoc_1d THEN data = assoc(descriptor.unit,bytarr(dims(0)), offset) ELSE $
           IF assoc_2d THEN data = assoc(descriptor.unit, bytarr(dims(0), dims(1)), offset) ELSE $
           IF assoc_3d THEN data = assoc(descriptor.unit, bytarr(dims(0), dims(1), dims(2)), offset) ELSE BEGIN
                                ; Associate with file descriptor since
                                ; this is the only simple way to lseek() in IDL; 
            IF rank EQ 1 THEN rawdata = assoc(descriptor.unit, bytarr(dims(0)), offset) ELSE $
              IF rank EQ 2 THEN rawdata = assoc(descriptor.unit, bytarr(dims(0), dims(1)), offset) ELSE $
              IF rank EQ 3 THEN rawdata = assoc(descriptor.unit, bytarr(dims(0), dims(1), dims(2)), offset)
                                ; Here's where we actually assign or
                                ; copy the data
            IF (N_ELEMENTS(data) EQ 0) OR (alloc) THEN data = rawdata(0) ELSE BEGIN ; copy and allocate
                                ; OK, here's where we copy data. if no
                                ; data is allocated then the statement
                                ; above will automatically do that for us 
               IF rank EQ 1 THEN data(*) =  rawdata(0) ELSE $ ; copy 1D
                 IF rank EQ 2 THEN data(*, *) =  rawdata(0) ELSE $ ; copy 2D
                 IF rank EQ 3 THEN data(*, *, *) =  rawdata(0) ; copy 3D
            ENDELSE
         ENDELSE
      END
      1:BEGIN
         IF assoc_e THEN data = assoc(descriptor.unit,intarr(1), offset) ELSE $
           IF assoc_1d THEN data = assoc(descriptor.unit,intarr(dims(0)), offset) ELSE $
           IF assoc_2d THEN data = assoc(descriptor.unit, intarr(dims(0), dims(1)), offset) ELSE $
           IF assoc_3d THEN data = assoc(descriptor.unit, intarr(dims(0), dims(1), dims(2)), offset) ELSE BEGIN
                                ; Associate with file descriptor since
                                ; this is the only simple way to lseek() in IDL; 
            IF rank EQ 1 THEN rawdata = assoc(descriptor.unit, intarr(dims(0)), offset) ELSE $
              IF rank EQ 2 THEN rawdata = assoc(descriptor.unit, intarr(dims(0), dims(1)), offset) ELSE $
              IF rank EQ 3 THEN rawdata = assoc(descriptor.unit, intarr(dims(0), dims(1), dims(2)), offset)
                                ; Here's where we actually assign or
                                ; copy the data
            IF (N_ELEMENTS(data) EQ 0) OR (alloc) THEN data = rawdata(0) ELSE BEGIN ; copy and allocate
                                ; OK, here's where we copy data. if no
                                ; data is allocated then the statement
                                ; above will automatically do that for us 
               IF rank EQ 1 THEN data(*) =  rawdata(0) ELSE $ ; copy 1D
                 IF rank EQ 2 THEN data(*, *) =  rawdata(0) ELSE $ ; copy 2D
                 IF rank EQ 3 THEN data(*, *, *) =  rawdata(0) ; copy 3D
            ENDELSE
         ENDELSE
      END
      2:BEGIN
         IF assoc_e THEN data = assoc(descriptor.unit,lonarr(1), offset) ELSE $
           IF assoc_1d THEN data = assoc(descriptor.unit,lonarr(dims(0)), offset) ELSE $
           IF assoc_2d THEN data = assoc(descriptor.unit, lonarr(dims(0), dims(1)), offset) ELSE $
           IF assoc_3d THEN data = assoc(descriptor.unit, lonarr(dims(0), dims(1), dims(2)), offset) ELSE BEGIN
                                ; Associate with file descriptor since
                                ; this is the only simple way to lseek() in IDL; 
            IF rank EQ 1 THEN rawdata = assoc(descriptor.unit, lonarr(dims(0)), offset) ELSE $
              IF rank EQ 2 THEN rawdata = assoc(descriptor.unit, lonarr(dims(0), dims(1)), offset) ELSE $
              IF rank EQ 3 THEN rawdata = assoc(descriptor.unit, lonarr(dims(0), dims(1), dims(2)), offset)
                                ; Here's where we actually assign or
                                ; copy the data
            IF (N_ELEMENTS(data) EQ 0) OR (alloc) THEN data = rawdata(0) ELSE BEGIN ; copy and allocate
                                ; OK, here's where we copy data. if no
                                ; data is allocated then the statement
                                ; above will automatically do that for us 
               IF rank EQ 1 THEN data(*) =  rawdata(0) ELSE $ ; copy 1D
                 IF rank EQ 2 THEN data(*, *) =  rawdata(0) ELSE $ ; copy 2D
                 IF rank EQ 3 THEN data(*, *, *) =  rawdata(0) ; copy 3D
            ENDELSE
         ENDELSE
      END
      3:BEGIN
         print, 'PRO ieeeread: Error... This data is Int64 and IDL has no 64-bit integer datatype.'
      END
      4:BEGIN
         IF assoc_e THEN data = assoc(descriptor.unit,fltarr(1), offset) ELSE $
           IF assoc_1d THEN data = assoc(descriptor.unit,fltarr(dims(0)), offset) ELSE $
           IF assoc_2d THEN data = assoc(descriptor.unit, fltarr(dims(0), dims(1)), offset) ELSE $
           IF assoc_3d THEN data = assoc(descriptor.unit, fltarr(dims(0), dims(1), dims(2)), offset) ELSE BEGIN
                                ; Associate with file descriptor since
                                ; this is the only simple way to lseek() in IDL; 
            IF rank EQ 1 THEN rawdata = assoc(descriptor.unit, fltarr(dims(0)), offset) ELSE $
              IF rank EQ 2 THEN rawdata = assoc(descriptor.unit, fltarr(dims(0), dims(1)), offset) ELSE $
              IF rank EQ 3 THEN rawdata = assoc(descriptor.unit, fltarr(dims(0), dims(1), dims(2)), offset)
                                ; Here's where we actually assign or
                                ; copy the data
            IF (N_ELEMENTS(data) EQ 0) OR (alloc) THEN data = rawdata(0) ELSE BEGIN ; copy and allocate
                                ; OK, here's where we copy data. if no
                                ; data is allocated then the statement
                                ; above will automatically do that for us 
               IF rank EQ 1 THEN data(*) =  rawdata(0) ELSE $ ; copy 1D
                 IF rank EQ 2 THEN data(*, *) =  rawdata(0) ELSE $ ; copy 2D
                 IF rank EQ 3 THEN data(*, *, *) =  rawdata(0) ; copy 3D
            ENDELSE
         ENDELSE
      END
      5:BEGIN
         IF assoc_e THEN data = assoc(descriptor.unit,dblarr(1), offset) ELSE $
           IF assoc_1d THEN data = assoc(descriptor.unit,dblarr(dims(0)), offset) ELSE $
           IF assoc_2d THEN data = assoc(descriptor.unit, dblarr(dims(0), dims(1)), offset) ELSE $
           IF assoc_3d THEN data = assoc(descriptor.unit, dblarr(dims(0), dims(1), dims(2)), offset) ELSE BEGIN
                                ; Associate with file descriptor since
                                ; this is the only simple way to lseek() in IDL; 
            IF rank EQ 1 THEN rawdata = assoc(descriptor.unit, dblarr(dims(0)), offset) ELSE $
              IF rank EQ 2 THEN rawdata = assoc(descriptor.unit, dblarr(dims(0), dims(1)), offset) ELSE $
              IF rank EQ 3 THEN rawdata = assoc(descriptor.unit, dblarr(dims(0), dims(1), dims(2)), offset)
                                ; Here's where we actually assign or
                                ; copy the data
            IF (N_ELEMENTS(data) EQ 0) OR (alloc) THEN data = rawdata(0) ELSE BEGIN ; copy and allocate
                                ; OK, here's where we copy data. if no
                                ; data is allocated then the statement
                                ; above will automatically do that for us 
               IF rank EQ 1 THEN data(*) =  rawdata(0) ELSE $ ; copy 1D
                 IF rank EQ 2 THEN data(*, *) =  rawdata(0) ELSE $ ; copy 2D
                 IF rank EQ 3 THEN data(*, *, *) =  rawdata(0) ; copy 3D
            ENDELSE
         ENDELSE
      END
   ENDCASE
   RETURN
END