MySQL Reference Manual for version 4.0.18.

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17.3.2 Well-Known Binary (WKB) Format

The Well-Known Binary (WKB) representation for geometric values is defined by the OpenGIS specifications. It is also defined in the ISO "SQL/MM Part 3: Spatial" standard.

WKB is used to exchange geometry data as binary streams represented by BLOB values containing geometric WKB information.

WKB uses 1-byte unsigned integers, 4-byte unsigned integers, and 8-byte double-precision numbers (IEEE 754 format). A byte is 8 bits.

For example, a WKB value that corresponds to POINT(1 1) consists of this sequence of 21 bytes (each represented here by two hex digits):

 
0101000000000000000000F03F000000000000F03F

The sequence may be broken down into these components:

 
Byte order : 01
WKB type   : 01000000
X          : 000000000000F03F
Y          : 000000000000F03F

Component representation is as follows:

WKB values for more complex geometry values are represented by more complex data structures, as detailed in the OpenGIS specification.



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