This is where the Service Provider can select the services that a Supplier will need to quote for on the Quote Request type.
In a Quote Request Project workflow, when the Service Provider selects Suppliers to send the Quote Request to, Suppliers providing the services set here will be listed as selectable options. The Service Provider is not limited to these Suppliers, however, other services / Suppliers can be selected when creating a Quote Request for a Customer.
For more information see Service Provider selects Suppliers.