The Operation Extender is not preceded by a valid Operation Code.
20
Cause . . . . . : The Operation Extender must be preceded by a valid Operation Code in positions 26 - 35. All data from the start of the Operation Extender to the end of the Operation entry is ignored.
Recovery . . . : Specify a valid Operation Code followed by the Operation Extender in positions 26 - 35 or remove the Operation Extender. Compile again.
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