Do we need to reset to starting number directly in PRD?

Hello

I have created a Z numbere range object, set the starting as 000001 to 999999. Pls. let me know

1) Once it reached the last number as 999999 then what happens, i mean, wht the number will be delivered the object/FM?

2) If we need to reset it back to starting point as 000001, then its duplicate key in the data base table right?

3) If we have to reset it to 000001 then do we need to do it PRD directly?

Thank you