The Message Definitions file for United States English is named TRD0LENU; it is provided on a release tape. The Assembler file for TRD0LENU is on the z/OS release tape as member CL2ASSEM. No action is required to use this file for messages in United States English. The file is provided as the basis for creating message definitions in other languages.
Message definitions are created though the use of Assembler macros that are assembled and link-edited (or bound) to produce a load module. Each load module contains all the CLIv2 messages for one language for a country. The distributed TRD0LENU also contains a second item to identify the current CLIv2 release.
This information is used by the DBCHQE Request-message-release query. While not required, this information can also be included in a customized message module during linkage editor or binder processing by including the distributed TRD0LENU module after the customized version (since all message table Control Sections are named TRD0L, the distributed one will be ignored since the customized one was first, but the other Control Section, named TRD2XRLS, does not exist in the customized version so will be included). But if included, it must not be first in the module: TRD0L, the Control Section name for the message table itself, must always be first, otherwise CLIv2 will abnormally terminate when attempting to construct a message.