Trigger Purchase requisition IDoc

Hi Experts ,

I want to trigger IDoc for purchase requisition.

Message type of PR is PREQCR1

and IDoc type is PREQCR101.

But I don't know how to trigger this IDoc. There is no message control for PR in NACE and also there is no option for output type in ME52n.

I searched through forums but didnt get any answer.

Please help

Thanks