Externally-Described File

For externally described files, if the EXTDESC keyword is not specified, the file name specified on the file definition is the name used to locate the record descriptions for the file. The following rules apply to externally described files:

• Input and output specifications for externally described files are optional. They are required only if you are adding RPG IV functions, such as control fields or record identifying indicators, to the external description retrieved.
• When an external description is retrieved, the record definition can be referred to by its record format name on the input, output, or calculation specifications. If the file is qualified, due to the QUALIFIED or LIKEFILE keywords, the qualified record format is referred to by both the file and record format, for example MYFILE.MYFMT.
• A record format name must be a unique symbolic name. If the file is qualified, due to the QUALIFIED or LIKEFILE keyword, the name of record format must be unique to the other formats of the file. If the file is not qualified, the name of the record format must be unique to the other names within the module.
• RPG IV does not support an externally described logical file with two record formats of the same name. However, such a file can be accessed if it is program described.