CDR file format: RIFF chunks

CorelDRAW 3 to X3 save a drawing as a RIFF file, and the drawing inside the ZIP packages of X4 and later is the same kind of stream. This page describes the chunks and lists as libcdr reads them, and as they appear in a CorelDRAW 6 file. Corel has not published any of it. All numbers are little-endian.

Chunks

Every chunk has the same eight-byte header. A reader should step over zero bytes before a header, as libcdr does: a chunk of odd length is followed by one.

Offset	Size	Field	Description
`0`	4	ID	Four ASCII characters, for example `vrsn`, `loda` or `bmp` with a space.
`4`	4	Length	The bytes of data after this field. Inside a compressed list it is an index into a table of lengths instead.
`8`	length	Data	For `RIFF` and `LIST`, a four-character list type and then more chunks; for any other ID, the chunk’s own fields.

File header

0ID RIFF4 bytes
4Length the rest of the file, from offset 84 bytes
8Form type CDR (or cdr) and the version character4 bytes
12Chunks vrsn first, then the rest of the drawingvaries

The first 12 bytes of a CorelDRAW 3 to X3 file.

Character at offset 11	Version	vrsn value
space	CorelDRAW 3	300
`4` to `9`	CorelDRAW 4 to 9	400 to 900
`A`, `B`, `C`	CorelDRAW 10, 11, 12	1000, 1100, 1200
`D`	CorelDRAW X3	1300
`E` and later	X4 and later, inside the ZIP package	1400 and up

vrsn: version

The first chunk. Its data is one unsigned 16-bit number, 100 times the major version. libcdr takes the version from here and uses it to decide how every later record is laid out; below 600 it reads coordinates and counts as 16 bits, from 600 as 32 bits.

Offset	Size	Field	Description
`0`	2	Version	For example `58 02`, 600, for CorelDRAW 6.

The tree

After vrsn and DISP, a CorelDRAW 6 file has a LIST doc of document tables, then one LIST page for each page. A page holds its flags and its layers; a layer holds its flags and its objects; an object holds its flags, its box and a list of its parts.

RIFF CDR6
  vrsn
  DISP                       preview picture
  LIST INFO                  IKEY, ICMT
  LIST doc
    mcfg                     page size and settings
    LIST fntt                font chunks
    LIST filt                fill chunks
    LIST otlt                outl chunks
    LIST stlt                styles
  LIST page                  one for each page, and one more first
    flgs
    LIST gobj
      LIST layr
        flgs
        LIST lgob
          LIST obj           or LIST grp for a group
            flgs
            bbox
            usdn
            LIST lgob
              loda           the object's shape and the ids of its fill and outline
              LIST trfl
                trfd         the object's transformation

libcdr does not draw a page whose flags have a non-zero third byte. In the CorelDRAW 6 file seen, only the first page list is marked so, and it has more layers than the others. Later versions keep the same lists but put most of them inside a cmpr list.

List types

List type	Holds
`doc`	Document settings (`mcfg`) and the tables of fonts, fills, outlines, styles, arrowheads and bitmaps.
`fntt`	The font table: `font` chunks.
`filt`	The fill table: `fill` chunks (libcdr also reads `fild`).
`otlt`	The outline table: `outl` chunks.
`stlt`	Styles. Up to CorelDRAW 6 a list of chunks; from CorelDRAW 7 libcdr reads it as one record.
`page`	A page: `flgs` and its layers.
`gobj`	The layers of a page, in CorelDRAW 6.
`layr`	A layer: `flgs` and its objects.
`obj`	An object.
`grp`	A group: the objects in it, and its own transformation.
`lgob`	The parts of a layer, object or group.
`trfl`	An object’s transformations: `trfd` chunks.
`cmpr`	A compressed list.
`INFO`	Standard RIFF information chunks such as `IKEY` and `ICMT`.

Chunk IDs

ID	Holds	Described
`vrsn`	The version.	above
`DISP`	The preview picture.	Preview picture
`mcfg`	Document settings, with the page size.	below
`flgs`	Flags of a page, layer or object.	below
`bbox`	An object’s bounding box.	below
`loda`, `lobj`	An object’s shape and the ids of its fill, outline and style.	Objects
`trfd`	A transformation matrix.	Objects
`fill`, `fild`	A fill.	Fills
`outl`	An outline.	Outlines
`font`	A font.	Fonts
`bmp`	A bitmap used by bitmap objects.	Bitmaps
`arrw`	An arrowhead shape.	not here
`txsm`	Text and its formatting. The layout changes in almost every version.	not here
`styd`	A style definition.	not here
`usdn`, `obbx`, `spnd`, `uidr`	An object’s number, oriented box, spline data and unique id.	not here
`ole2`, `olel`	An embedded OLE object (a compound file, `D0 CF 11 E0`) and its link.	not here
`cmx1`	In the CorelDRAW 6 file seen, the drawing again as a Corel Presentation Exchange (CMX) file: `RIFF` with form type `CMX1`.	not here
`ccmm`	Not known.	not here

mcfg: page size

libcdr reads only the page size from this chunk. Where it is depends on the version; what the bytes before and after it hold is not known.

Version	Bytes before the size	Then
3	2	Four coordinates: left, bottom, right, top. The size is the difference.
4 and 5	0	Width, then height, as coordinates.
6	28	Width, then height.
7 and 8	0	Width, then height.
9 to 12	4	Width, then height.
X3 and later	12	Width, then height.

A coordinate is a signed 16-bit number of thousandths of an inch up to version 5, and a signed 32-bit number of 1/254,000 inch from version 6. The page’s centre is the origin, and y grows upwards.

flgs: flags

Four bytes, read as an unsigned 32-bit number. libcdr uses two things in them. A page whose flags have a non-zero third byte (flags & 0x00FF0000) is not drawn. A layer whose third byte is zero and which has bit 0x100 set is not drawn either. What the other bits mean is not known.

bbox: bounding box

Offset (6 and later)	Size	Field
`0`	4	x of one corner
`4`	4	y of that corner
`8`	4	x of the opposite corner
`12`	4	y of the opposite corner

Up to version 5 each coordinate is 2 bytes, so the chunk is 8 bytes.

.CDR File Format – RIFF chunks