Service Material Type & Purchase

Hi,

We have a Material Type u2018ZSERu2019 which is defined as u201CService Materialu201D. Its Item category code has been defined as u2018LEISu2019 (Service w/o Delivery), because itu2019s a service we provide to our customers which need to record in our sales orders. User departments for ZSER type also include Purchasing.

Now if I simply create a Material item of type ZSER, can it also be purchased via o Purchased Order?

If so how can I restrict raising PRs or POs for any materials of type ZSER?