OpenGIS. The OpenGIS specification defines functions that test the relationship between
two geometry values. MySQL originally implemented these functions such that they used
object bounding rectangles and returned the same result as the corresponding MBR-based
functions. Corresponding versions are now available that use precise object shapes. These
versions are named with an ST_ prefix. For example, Contains()  uses object bounding
rectangles, whereas ST_Contains()  uses object shapes. For more information, see
Section 22.214.171.124.2, “Functions That Test Spatial Relationships Between Geometries”.
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