  .. class:: Envelope(expression, **extra)
  
  *Availability*: `MySQL
  <https://dev.mysql.com/doc/refman/en/gis-general-property-functions.html#function_st-envelope>`__,
  `Oracle
  <https://docs.oracle.com/database/121/SPATL/sdo_geom-sdo_mbr.htm#GUID-646638D0-2C5F-490A-AF63-DE9B7A4C97C1__CHDJCEIH>`__,
  `PostGIS <https://postgis.net/docs/ST_Envelope.html>`__, SpatiaLite
  
  Accepts a single geographic field or expression and returns the geometry
  representing the bounding box of the geometry.
  
 
</s> remove `Oracle <https://docs.oracle.com/database/121/SPATL/sdo_geom-sdo_mbc.htm#SPATL1554>`_
 </s> add `Oracle <https://docs.oracle.com/en/database/oracle/oracle-database/18/spatl/
SDO_GEOM-reference.html#GUID-82A61626-BB64-4793-B53D-A0DBEC91831A>`_ </s> remove   columns`_.

  .. _`identity columns`: https://docs.oracle.com/database/121/DRDAA/migr_tools_feat.htm#DRDAA109
 </s> add   columns <https://docs.oracle.com/en/database/oracle/oracle-database/18/drdaa/
  intro-to-tools-and-products-supporting-migraiton.html#GUID-14E4817B-F3BC-4D99
  -B471-A0ACDC303CC9>`__. </s> remove .. [#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.
 </s> add .. [#fnsdorelate] *See* `SDO_RELATE documentation <https://docs.oracle.com/en/
   database/oracle/oracle-database/18/spatl/spatial-operators-reference.html#
   GUID-97C17C18-F05E-49B4-BE11-E89B972E2A02>`_, from the Oracle Spatial and
   Graph Developer's Guide. </s> remove .. _Oracle manual: https://docs.oracle.com/database/121/NLSPG/toc.htm
.. _section 2: https://docs.oracle.com/database/121/NLSPG/ch2charset.htm#NLSPG002
.. _section 11: https://docs.oracle.com/database/121/NLSPG/ch11charsetmig.htm#NLSPG011
 </s> add .. _Oracle manual: https://docs.oracle.com/en/database/oracle/oracle-database/18/nlspg/index.html
.. _section 2: https://docs.oracle.com/en/database/oracle/oracle-database/18/nlspg/choosing-character-set.html
.. _section 11: https://docs.oracle.com/en/database/oracle/oracle-database/18/nlspg/character-set-migration.html </s> remove     .. _Choosing a Time Zone File: https://docs.oracle.com/database/121/NLSPG/ch4datetime.htm#NLSPG258
 </s> add     .. _Choosing a Time Zone File: https://docs.oracle.com/en/database/oracle/
       oracle-database/18/nlspg/datetime-data-types-and-time-zone-support.html
       #GUID-805AB986-DE12-4FEA-AF56-5AABCD2132DF
`Oracle <https://docs.oracle.com/en/database/oracle/oracle-database/18/spatl/
SDO_GEOM-reference.html#GUID-646638D0-2C5F-490A-AF63-DE9B7A4C97C1__CHDJCEIH>`__,
  .. class:: Envelope(expression, **extra)
  
  *Availability*: `MySQL
  <https://dev.mysql.com/doc/refman/en/gis-general-property-functions.html#function_st-envelope>`__,
`Oracle <https://docs.oracle.com/en/database/oracle/oracle-database/18/spatl/
SDO_GEOM-reference.html#GUID-646638D0-2C5F-490A-AF63-DE9B7A4C97C1__CHDJCEIH>`__,
`Oracle <https://docs.oracle.com/en/database/oracle/oracle-database/18/spatl/
SDO_GEOM-reference.html#GUID-646638D0-2C5F-490A-AF63-DE9B7A4C97C1__CHDJCEIH>`__,
  `PostGIS <https://postgis.net/docs/ST_Envelope.html>`__, SpatiaLite
  
  Accepts a single geographic field or expression and returns the geometry
  representing the bounding box of the geometry.
  
keep keep keep keep replace replace keep keep keep keep keep
 Updated Oracle docs links to Oracle 18c. 
docs/ref/contrib/gis/functions.txt