Notes on the MapInfo® Native table format
by Anssi Joutsiniemi
and Robert Edwards
The information provided in this document is not
guaranteed to be accurate. The authors assume no responsibility for
any trouble you may experience as a result of using this
information. Use at your own risk.
In the spirit of the
Open Source Initiative, this document may be freely distributed.
You may make changes to the original and redistribute, but all
copies must retain the orignal title, authors' names, and
disclaimer.
If you do make additions or corrections, the author
would appreciate receiving an E-mail copy of your updated document
or a URL to its location. - March 2000
MapInfo is a registered trademark of MapInfo Corporation.
DOCUMENTATION CONVENTIONS
In this brief introduction all offsets are relative to the beginning
of each block. Values preceded by "&H" are hexadecimal.
Naming convention is invented by the author, since no documentation
on the native MapInfo® file format is currently available.
In this documentation notations are marked as follows:
[?] talented guess
[??] not so good guess
[!] value that seems to be a constant
General Notes on MapInfo® Tables
MapInfo® Native Table consists of
files with following suffixes:
| .TAB: | table structure in ASCII format (required) |
| .DAT: | table date storage in binary format (required) |
| .MAP: | storage of map objects in binary format (optional) |
| .ID: | links to the .map file (optional, but required if .map file exists) |
| NOT described in this document: |
| .IND: | data of indexed fields in binary format (optional) |
The structure of MapInfo® .dat file is virtually identical to dBase IV
data format. The MapInfo® .id file data is stored in 32 bit Integers, each value points
to an object in the Object Definition Blocks (see below) because
the record order in .id file is same as in .dat file (i.e. RowID)
including deleted record which have a value of &H0.
MapInfo® .map file is organized in blocks of &H200 bytes. (Beginning with Version 500
the Header Block is extended by &H200 bytes.) Each block is identified by first byte.
The six block types are:
- HEADER BLOCK(BlockID 0)
- General information of table coordinate system and internal
structure
- INDEX BLOCK (BlockID 1)
- Index to locate map objects on Object Definition Blocks
- OBJECT DEFINITION BLOCK (BlockID 2)
- General information on map objects
- COORDINATE DEFINITION BLOCK (BlockID 3)
- Coordinate storage block
- DELETED BLOCK (BlockID 4)
- Re-usable block
- RESOURCE BLOCK (BlockID 5)
- List of pen, brush, font and symbol resources of table
The byte order is little-endian (from least
significant byte to most significant byte).
Map objects can be accessed in either of two ways.
One is through the offset in .id file which is a means of accessing the
object information associated with an attribute. The other is what I have used
in my Recover.mbx which loops through the Index Block
to gain information on all Object Definition Blocks. This is useful for
a more sophisticated use when objects are selected according to their
MBR (Minimum Bounding Rectangle).
Robert Edwards pointed out that the coordinates and
distances in an object definition are defined using either 16 bit
integers (MI:SmallInt) or 32 bit integers (MI:Integers). Inspection
of the object code numbering scheme indicates that there is the
possiblity of another set of object definition, perhaps based on 64 bit coordinates,
but there is no evidence that such a feature has been implemented.
According to Edwards, short coordinate
precision is used if all the coordinates and distances for an object
can be expressed as differences less than +-2^15. Short coordinate
values are added to base coordinate value (base coordinates are located
either in the base of the Object Definition Block or in the object
itself) and this sum is converted to floating point coordinates using
the X/Y offsets and X/Y scales in Header Block.
Data stored in Coordinate Definition Blocks contains the actual coordinate data
and header information of each section of holy or multisectioned
polygon. So the data of one map object consists of numbers of Section
headers, which is followed by coordinate values of all object sections.
Note also: Object Definition Block (Block type code 2) is called Object
Definition Block in Open Source Software. Maybe one day all this stuff is put
together, but for know it is far more important that you play with it make it right.
LIST OF KNOWN BLOCKS AND BLOCK OFFSETS:
HEADER BLOCK (BlockType 0)
offset length count description
--------------------------------------------------------------
&H0 1 1 Header Block identifier (Value: &H0) [!]
&H1 1 1 Header Block header
:
: Unknown (For length of header data offset see &H163)
:
&H33/&H2D/&H27/&H1F
:
: (Value &H0 [!])
:
&HFF
&H100 4 1 Magic Number (&H28757B2 i.e.42424242) [?]
&H104 2 1 Map File Version (not equal to table version)
&H106 2 1 Unknown value: &H200 [!], BlockSize[??]
&H108 8 1 CoordSysToDistUnits: Miles/LatDegree for Lat/Long maps
1.0 for all others [!]
&H110 4 4 Coordinates of Minimum Bounding Rectangle (MBR)
&H120 4 4 Coordinates of Default View of table
&H130 4 1 Offset of Object Definition Index (see also &H15F)
&H134 4 1 Offset of the beginning of Deleted Block sequence
&H138 4 1 Offset of Resources Block
&H13C 4 1 Number of Symbol elements
&H140 4 1 Number of Line elements
&H144 4 1 Number of Region elements
&H148 4 1 Number of Text elements
&H14C 4 1 MaxCoordBufSize
&H14E 14 1 14 Unknown bytes (Probably reserved and set to zero)
&H15E 1 1 Map File Distance Units
For detailed information on distance unit values see:
MapInfoProgramDirectory/Ut/Reproject/MapInfoUnits.db
&H15F 1 1 Type of Element Indexing data (see also &H130)
0 = NoData
1 = Object Definition Block (NoIndex block)
2 = Index Block
&H160 1 1 CoordPrecision Value:6 for Lat/Long maps
Value:8 for Cartesian maps
Value:1 for Projected maps
&H161 1 1 CoordOriginCode Value:2 for Lat/Long maps
Value:1 for Cartesian and Projected maps
&H162 1 1 ReflectAxisCode Value:1 for Lat/Long maps
Value:0 for Cartesian and Projected maps
&H163 1 1 ObjLenArraySize (at start of this block)
&H164 1 1 Number of pen resources
&H165 1 1 Number of brush resources
&H166 1 1 Number of symbol resources
&H167 1 1 Number of text resources
&H168 2 1 Number of Resource Blocks
&H169 3 1 Unknown(probably reserved and set to zero)
&H16D 1 1 Projection type
For detailed information on internal projection values see:
MapInfoProgramDirectory$>/Ut/Reproject/MapInfoProj.db
&H16E 1 1 Datum (See also &H1C0, &H1C8, &H1D0)
(Not always equal to value in MapInfow.prj)
For detailed information on internal datum values see:
<MapInfo ProgramDirectory$>/Ut/Reproject/MapinfoDatums.db
&H16F 1 1 Units of coordinate system
(Values equal to &H15E)
&H170 8 4 XScale, YScale, XOffset, YOffset
&H190 8 1 Projection parameter 1.
&H198 8 1 Projection parameter 2.
&H1A0 8 1 Projection parameter 3.
&H1A8 8 1 Projection parameter 4.
&H1B0 8 1 Projection parameter 5.
&H1B8 8 1 Projection parameter 6.
&H1C0 8 1 Datum shift X
&H1C8 8 1 Datum shift Y
&H1D0 8 1 Datum shift Z
&H1D8 8 5 Datum parameters
.
.
.
&H1FF
Version 500 extension (see &H104)
--------------------------------------------------------------
&H200 1 1 Value &H1 if in use
&H201 1 1 Affine unit name
&H208 8 6 Affine parameters A, B, C, D, E, F
(see Appendix H)
&H238
: Probably Not In Use (and not padded w/ zeros)
&H3FF
INDEX BLOCK (BlockType 1)
Index Block header (length: &H4)
---------------------------------------------------------------
&H0 1 1 Index Block identifier (Value: &H1) [!]
&H1 1 1 Link
&H2 1 2 Number of Index data blocks
Index data (length: &H14)
---------------------------------------------------------------
&H0 4 4 Object Definition Block MBR (XMin, YMin, XMax, YMax)
&H10 4 1 Object Definition Block offset
Object Definition Block (BlockType 2)
Object Definition Block header (length: &H14)
---------------------------------------------------------------
&H0 1 1 Object Definition Block identifier (Value: &H2) [!]
&H1 1 1 Link to next Object Definition Block
&H2 2 1 Bytes To Follow (length of ODB data)
&H4 4 2 Base coordinate values for short object types
Object Definition data items, which are identified by a code in the first byte, are
arrayed in an Object Definition Block after the header. The items in an Object
Definition Block reference coordinate and section definitions in
an associated Coordinate Definition Block (or Blocks). For details about
object types see Edwards' notes.
---------------------------------------------------------------
ShortPoint [ID 1] (length: &HA): [?]
&H0 1 1 Identifier (Value: &H1) [!]
&H1 4 1 RowID - Validity: (+0 = Valid; +&H40000000 = Deleted)
&H5 2 2 Coordinate value
&H9 1 1 Symbol type number from Resource Block
LongPoint [ID 2] (length: &HE):
&H0 1 1 Identifier (Value: &H2) [!]
&H1 4 1 RowID - Validity: (+0 = Valid; +&H40000000 = Deleted)
&H5 4 2 Coordinate value
&HD 1 1 Symbol type number from Resource Block
ShortLine [ID 4] (length: &HE):
&H0 1 1 Identifier (Value: &H4) [!]
&H1 4 1 RowID - Validity: (+0 = Valid; +&H40000000 = Deleted)
&H5 4 2 Coordinate value
&HD 1 1 Line type number from Resource Block
LongLine [ID 5] (length: &H16):
&H0 1 1 Identifier (Value: &H5) [!]
&H1 4 1 RowID - Validity: (+0 = Valid; +&H40000000 = Deleted)
&H5 4 4 MBR
&H15 1 1 Line type number from Resource Block
ShortPolyline [ID 7] (length: &H1A):
&H0 1 1 Identifier (Value: &H7) [!]
&H1 4 1 RowID - Validity: (+0 = Valid; +&H40000000 = Deleted)
&H5 4 1 Offset of coordinate data in Coordinate Definition Block
&H9 4 1 Bytes to read for coordinates from Coordinate Definition Block [?]
&HD 2 2 Label location coordinates
&H11 2 4 MBR
&H19 1 1 Line type number from Resource Block
LongPolyline [ID 8] (length: &H26):
&H0 1 1 Identifier (Value: &H8) [!]
&H1 4 1 RowID - Validity: (+0 = Valid; +&H40000000 = Deleted)
&H5 4 1 Offset of coordinate data in Coordinate Definition Block
&H9 4 1 Bytes to read for coordinates from Coordinate Definition Block [?]
&HD 4 2 Label location coordinates
&H15 4 4 MBR
&H25 1 1 Line type number from Resource Block
ShortArc [ID 10] (length: &H16):
&H0 1 1 Identifier (Value: &HA) [!]
&H1 4 1 RowID - Validity: (+0 = Valid; +&H40000000 = Deleted)
&H5 4 2 MBR of defining ellipse
&HD 4 2 MBR of the arc
&H15 1 1 Line type number from Resource Block
LongArc [ID 11] (length: &H26):
&H0 1 1 Identifier (Value: &HB) [!]
&H1 4 1 RowID - Validity: (+0 = Valid; +&H40000000 = Deleted)
&H5 4 4 MBR of defining ellipse
&15 4 4 MBR of the arc
&H25 1 1 Line type number from Resource Block
ShortRegion [ID 13] (length: &H25):
&H0 1 1 Identifier (Value: &HD) [!]
&H1 4 1 RowID - Validity: (+0 = Valid; +&H40000000 = Deleted)
&H5 4 1 Offset of coordinate data in Coordinate Definition Block
&H9 4 1 Bytes to read for coordinates from Coordinate Definition Block [??]
&HD 2 1 Section count
&HF 4 2 Label X,Y
&H13 4 4 MBR
&H23 1 1 Line type number from Resource Block
&H24 1 1 Brush type number from Resource Block
LongRegion [ID 14] (length: &H29):
&H0 1 1 Identifier (Value: &HE) [!]
&H1 4 1 RowID - Validity: (+0 = Valid; +&H40000000 = Deleted)
&H5 4 1 Offset of coordinate data in Coordinate Definition Block
&H9 4 1 Bytes to read for coordinates from Coordinate Definition Block [??]
&HD 2 1 Section count
&HF 4 2 Label X,Y
&H17 4 4 MBR
&H27 1 1 Line type number from Resource Block
&H28 1 1 Brush type number from Resource Block
ShortText [ID 16] (length: &H27)
&H0 1 1 Identifier (Value: &H10) [!]
&H1 4 1 RowID - Validity: (+0 = Valid; +&H40000000 = Deleted)
&H5 4 1 Offset of text body in Coordinate Definition Block
&H9 2 1 Number of characters in text body
&HB 2 1 Justification spacing arrowtype:
flag 2^1 - centered text
flag 2^2 - right aligned text
flag 2^3 - line spacing 1.5
flag 2^4 - line spacing 2.0
flag 2^5 - label line: simple
flag 2^6 - label line: arrow
&HD 2 1 Text rotation angle (0.1 degrees)
&HF 1 1 FontStyle #1:
flag 2^0 - bold text
flag 2^1 - italic text
flag 2^2 - underlined text
flag 2^3 - overlined text
flag 2^4 - unknown
flag 2^5 - shadowed text
&H10 1 1 FontStyle #2:
flag 2^0 - box background
flag 2^1 - halo background
flag 2^2 - All Caps
flag 2^3 - Expanded
&H11 3 1 Foreground color
&H14 3 1 Background color
&H17 2 2 Arrow endpoint coordinates
&H1B 2 1 Height
&H1D 1 1 Font name index
&H1E 2 4 MBR
&H26 1 1 Pen type from Resource Block
LongText [ID 17] (length: &H32)
&H0 1 1 Identifier (Value: &H11) [!]
&H1 4 1 RowID - Validity: (+0 = Valid; +&H40000000 = Deleted)
&H5 4 1 Offset of text body in Coordinate Definition Block
&H9 2 1 Number of characters in text body
&HC 2 1 Justification spacing arrowtype:
flag 2^1 - centered text
flag 2^2 - right aligned text
flag 2^3 - line spacing 1.5
flag 2^4 - line spacing 2.0
flag 2^5 - label line: simple
flag 2^6 - label line: arrow
&HD 2 1 Text rotation angle (0.1 degrees)
&HF 1 1 FontStyle #1:
flag 2^0 - bold text
flag 2^1 - italic text
flag 2^2 - underlined text
flag 2^3 - overlined text
flag 2^4 - unknown
flag 2^5 - shadowed text
&H10 1 1 FontStyle #2:
flag 2^0 - box background
flag 2^1 - halo background
flag 2^2 - All Caps
flag 2^3 - Expanded
&H11 3 1 Foreground color
&H14 3 1 Background color
&H17 4 2 Arrow endpoint coordinates
&H1F 1 4 Height
&H20 1 1 Font name index
&H30 4 4 MBR
&H31 1 1 Pen type from Resource Block
ShortRectangle [ID 19] (length: &HF):
&H0 1 1 Identifier (Value: &H10) [!]
&H1 4 1 RowID - Validity: (+0 = Valid; +&H40000000 = Deleted)
&H5 2 4 MBR
&HD 1 1 Line type number in Resource Block
&HE 1 1 Brush type number in Resource Block
LongRectangle [ID 20] (length: &H17):
&H0 1 1 Identifier (Value: &H17) [!]
&H1 4 1 RowID - Validity: (+0 = Valid; +&H40000000 = Deleted)
&H5 4 4 MBR
&H15 1 1 Line type number from Resource Block
&H16 1 1 Brush type number from Resource Block
ShortRoundRectangle [ID 22] (length: &H13):
&H0 1 1 Identifier (Value: &H16) [!]
&H1 4 1 RowID - Validity: (+0 = Valid; +&H40000000 = Deleted)
&H5 2 1 XRadius
&H7 2 1 YRadius
&H9 2 4 MBR
&H11 1 1 Line type number from Resource Block
&H12 1 1 Brush type number from Resource Block
LongRoundRectangle [ID 23] (length: &H1F):
&H0 1 1 Identifier (Value: &H16) [!]
&H1 4 1 RowID - Validity: (+0 = Valid; +&H40000000 = Deleted)
&H5 4 1 XRadius
&H9 4 1 YRadius
&HD 4 4 MBR
&H1D 1 1 Line type number from Resource Block
&H1E 1 1 Brush type number from Resource Block
ShortEllipse [ID 25] (length: &HF):
&H0 1 1 Identifier (Value: &H1A) [!]
&H1 4 1 RowID - Validity: (+0 = Valid; +&H40000000 = Deleted)
&H5 2 4 MBR
&HD 1 1 Line type number from Resource Block
&HE 1 1 Brush type number from Resource Block
LongEllipse [ID 26] (length: &H17):
&H0 1 1 Identifier (Value: &H1A) [!]
&H1 4 1 RowID - Validity: (+0 = Valid; +&H40000000 = Deleted)
&H5 4 4 MBR
&H15 1 1 Line type number from Resource Block
&H16 1 1 Brush type number from Resource Block
Coordinate Definition Block (BlockType 3)
Coordinate Definition Block header (length: &H8)
---------------------------------------------------------------
&H0 2 1 Coordinate Definition Block identifier (Value: &H3) [!]
&H2 2 1 Bytes To Follow
&H4 4 1 Offset to Coordinates
Short Poly Section header (length: &H10)
---------------------------------------------------------------
&H0 2 1 Number of coordinates
&H2 2 1 Number of holes
&H4 2 4 Section MBR coordinates
&H4 4 1 Offset to coordinates
Long Poly Section header (length: &H18)
---------------------------------------------------------------
&H0 2 1 Number of coordinates
&H2 2 1 Number of holes
&H4 4 4 Section MBR coordinates
&H4 4 1 Offset to coordinates
DELETED BLOCK (BlockType 4) [?]
Deleted Block header (length: &H8)
---------------------------------------------------------------
&H0 1 1 Deleted Block identifier (Value: &H4) [!]
&H1 1 1 Unknown
&H2 2 1 Bytes To Follow
&H4 4 1 Offset of next Deleted block
RESOURCE BLOCK (BlockType 5)
Resource Block header (length: &H8)
---------------------------------------------------------------
&H0 1 1 Resource Block identifier (Value: &H5) [!]
&H1 1 1 Unknown
&H2 2 1 Bytes To Follow
&H4 4 1 Offset of next Deleted block
Resource types identified by the first byte:
---------------------------------------------------------------
ID 1 Pen resource (length:&HB)
&H0 1 1 Resource identifier (Value: &H1) [!]
&H1 4 1 Number of elements using this resource
&H5 1 1 Line weight (pixels)
&H6 1 1 Line style
&H7 1 1 Line weight (points)
&H8 3 1 Line color
ID 2 Brush resource (length:&HD)
&H0 1 1 Resource identifier (Value: &H2) [!]
&H1 4 1 Number of elements using this resource
&H5 1 1 Brush style
&H6 1 1 Unknown
&H7 3 1 Foreground color
&HA 3 1 Background color
ID 3 Font resource (length:&H25)
&H0 1 1 Resource identifier (Value: &H3) [!]
&H1 4 1 Number of elements using this resource
&H5 32 1 Name of a font
ID 4 Symbol resource (length:&HD)
&H0 1 1 Resource identifier (Value: &H4) [!]
&H1 4 1 Number of elements using this resource
&H5 1 1 Unknown
&H6 1 1 Unknown
&H7 1 1 Unknown
&H8 1 1 Unknown
&H9 4 1 Unknown
RELATED LINKS
MapInfo TAB file "open source" documentation by Robert Edwards
[http://members.aol.com/MapToolsCompany/tabdef.txt]
Open Source C++ library to read and write MapInfo by Daniel Morissette
[http://pages.infinit.net/danmo/e00/index-mitab.html]
Recover.mbx by author
[recover.zip - recovers records that have been marked for deletion]
