Where is `COMMENT ON' syntex documented

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I've been trying to find the `comment on' syntax so I can add comments
to my tables, but have had no luck.  Where is this hiding...?

roland
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Roland B. Roberts, PhD                  Custom Software Solutions
roberts@panix.com                      76-15 113th Street, Apt 3B
rbroberts@acm.org                          Forest Hills, NY 11375

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