These constructors mirror the Table ones with additional checking on validity (verifying that the MSFreqOffset will have the required columns and keywords) An exception is thrown if the constructed Table is not a valid MSFreqOffset
As with tables, the destructor writes the table if necessary. Additional checking is done here to verify that all required columns are still present. If it is NOT valid, it will write the table and then throw an exception.
Assignment operator, reference semantics
Make a special copy of this Table which references all columns from this Table except those mentioned; those are empty and writable. Each forwarded column has the same writable status as the underlying column. The mentioned columns all use the AipsIO storage manager. This function is inherited from MSTable and unlikely to be of use, except in the class MeasurementSet (see comment there)..
Initialize the statics appropriately. This does not need to be called by users, it is called by the implementation class MSTableImpl.