+ conversation integer /*id of root notice in this conversation' */ references notice (id),
+ lat decimal(10,7) /* comment 'latitude'*/ ,
+ lon decimal(10,7) /* comment 'longitude'*/ ,
+ location_id integer /* comment 'location id if possible'*/ ,
+ location_ns integer /* comment 'namespace for location'*/ ,
+ repeat_of integer /* comment 'notice this is a repeat of' */ references notice (id)