Adding Superdescriptors using SYSAOS

I am trying to add superdescriptors to an existing file using SYSAOS.
Using the ADACMP utility syntax.

The utility returns the error message ‘superdescriptors may not be added to an existing FDT’.

I also included the command (ADACMP FDT=xxx) receive the same error.

Hi tjames,
to add a descriptor there is also the need not only to add this information to the FDT but also to build up the index. If there are already records in the file then these values will be taken to build up the index. If there are no values in minimum an empty entry has to be added.
To accomplish this you have either to use ADAINV (batch utility) or use in AOS in the menu - FDT/SDT Definition / Modification - the function I- online invert.
Regards,
Ursula Noll