The EXTDESC keyword must be specified before any keywords that reference record format names; the keyword is ignored.
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Cause . . . . . : Another keyword such as INCLUDE or SFILE was specified prior to the EXTDESC keyword. The file used for the external descriptions defaults to the file specified in position 7 of the File specification.
Recovery . . . : Specify the EXTDESC keyword before any other keywords that reference record format names.