OPEN DATASET statement

Hi experts,

How can I identify when I need to use "Encoding Default" or not in a OPEN DATASET statement?

I tried to see the version of my system, but both that I have are ECC 6, and both are No-Unicode, but one of them need to insert the ENCODING DEFAULT and the other don't.

Ex:

OPEN DATASET vl_archive FOR OUTPUT IN TEXT MODE.

or

OPNE DATASET vl_archive FOR OUTPUT IN TEXT MODE ENCODING DEFULT.

Thanks for your help!

Best Regards

Victor Marquise