"commented" => ["type" => "datetime", "not null" => "1", "default" => NULL_DATE, "comment" => "Date of last comment/reply to this item"],
"received" => ["type" => "datetime", "not null" => "1", "default" => NULL_DATE, "comment" => "datetime"],
"changed" => ["type" => "datetime", "not null" => "1", "default" => NULL_DATE, "comment" => "Date that something in the conversation changed, indicating clients should fetch the conversation again"],
"commented" => ["type" => "datetime", "not null" => "1", "default" => NULL_DATE, "comment" => "Date of last comment/reply to this item"],
"received" => ["type" => "datetime", "not null" => "1", "default" => NULL_DATE, "comment" => "datetime"],
"changed" => ["type" => "datetime", "not null" => "1", "default" => NULL_DATE, "comment" => "Date that something in the conversation changed, indicating clients should fetch the conversation again"],