Highest byte is stores byte order, dimension, nomem and geotype as follows: bo: byte order, 1 for little endian(ndr), 0 for big endian(xdr); Currently it must be always wkb_ndr since it is MySQL's portable geometry format.
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Highest byte is stores byte order, dimension, nomem and geotype as follows: bo: byte order, 1 for little endian(ndr), 0 for big endian(xdr); Currently it must be always wkb_ndr since it is MySQL's portable geometry format.
dimension: 0~3 for 1~4 dimensions; nomem: indicating whether this object has its own memory. If so, the memory is released when the object is destroyed. Some objects may refer to an existing WKB buffer and access it read only. geotype: stores the wkbType enum numbers, at most 32 values, valid range so far: [0, 7] and 31.
nybytes: takes the following 30 bits, stores number of effective and valid data bytes of current object's wkb data.
props: bits OR'ed for various other runtime properties of the geometry object. Bits are defined above. No properties are stored permanently, all properties here are specified/used at runtime while the Geometry object is alive. zm: not used now, always be 0, i.e. always 2D geometries. In future, they represent Z and/or M settings, 1: Z, 2: M, 3: ZM. unused: reserved for future use, it's unused now.
1.9.2