.. [#fnde9im] *See* `OpenGIS Simple Feature Specification For SQL <http://www.opengis.org/docs/99-049.pdf>`_, at Ch. 2.1.13.2, p. 2-13 (The Dimensionally Extended Nine-Intersection Model).
.. [#fnsdorelate] *See* `SDO_RELATE documentation <https://docs.oracle.com/database/121/SPATL/sdo_relate.htm#SPATL1039>`_, from the Oracle Spatial and Graph Developer's Guide.
GUID-97C17C18-F05E-49B4-BE11-E89B972E2A02>`_, from the Oracle Spatial and
Graph Developer's Guide.
.. [#fncovers] For an explanation of this routine, read `Quirks of the "Contains" Spatial Predicate <https://lin-ear-th-inking.blogspot.com/2007/06/subtleties-of-ogc-covers-spatial.html>`_ by Martin Davis (a PostGIS developer).