When you specify one or more techniques for a particular character conversion, z/OS Unicode Services loads all appropriate tables for the requested conversion into the image. If you do not specify any technique, then Unicode Services loads all available tables for the requested conversion into the image. For example, if you specify FROM-CCSID=1208, TO-CCSID=875, and technique=ERC, then z/OS Unicode Services will load tables for 1208-875-E, 1208-875-R, or 1208-875-C. Additional tables will be loaded if no technique is specified on the request. At run time, if a request for a conversion does not include a technique, Unicode uses a default search order, R E C L M and 0 - 9, to assign a conversion table to the request.

Composite conversions (those that require different techniques in the intermediate steps) require the use of sub CCSIDs to perform a conversion. z/OS Unicode Services determines those techniques that will be used and stores them into the image. If you do not specify any technique for a composite conversion, then the z/OS Unicode Services loads only the first table found for each sub CCSID.

CCSID 1200 is a special case since it is a virtual CCSID that represents the latest UTF-16 CCSID supported. When CCSID 1200 is specified, it is converted to the latest Unicode value supported for the conversion in question. This will result in the value of 13488, 175843, 21680, or 42160 used for the conversion.