how to block articlee for purchases

we are planning to block some of articles for purchases. However we want to allow for stock transfers using stock transfer requests( ME21N-UB doc type).

when i kept 01 Blocked for procment/whse in X-site status of baisc data tab system is not allowing for stock transfer order creation also.

plz suggest how to block articles for purchases without impacting for stock transfers.

what is the usage of follwing selections for blocking

01 Blocked for procment/whse

02 Blocked for task list/BOM

03 Blocked for Purchasing