Hi Reynaldo,
In BW there is a limited set of Time Characteristics and you are not able to create new custom Time Characteristics. You can only create a new Characteristic with or w/o reference to an existing Time Characteristic.
In your case I don't think you can reference to an existing Time Characteristic. So you have to define a custom Characteristic.
Please be aware that it won't support automatic time conversion. I cannot judge if that would be required.
Best regards,
Sander