When comparing Adaptive Server Enterprise column types and lengths with the metadata obtained from a remote server, Unicode datatypes in the proxy table are allowed under the following circumstances:
The remote server datatype for a column is either unichar or univarchar with equal length (expressed in characters, not bytes)
The remote server datatype for a given column is char or varchar. In this case, it will be the responsibility of CIS to perform conversions to Unicode on data fetched from the remote server, and conversions from Unicode to the default Adaptive Server Enterprise character set (UTF8) on data transmitted as part of DML commands (select, insert, delete, update).
The remote server datatype for a Unicode column is binary or varbinary. In this case, the length of the remote server column must be twice the length of the Unicode column. In this case, CIS performs conversions as required when transmitting data to or from the remote server.
No other datatype mapping for Unicode datatypes is allowed when mapping a proxy table to a remote table. Other types result in a type mismatch error. Using this mechanism, it is possible to convert data from legacy systems into Unicode simply by creating a proxy table that maps a Unicode column to an existing char or varchar column.