it is correct saying the following about services?
<b>Service master</b> and service category are only for buying services. This means you can create service master for creating service order.
<b>Material Type DIEN</b> is only use to create service material, which we are using to sale the services.It is mainly for customer service.
It is mandatory managing customer services functionality with material type DIEN?
The definition of service master and Material type DIEN is correct.