What is controlled by the item category of a sales document item? (Choose three)

You want to restrict the materials a customer can order.
What do you use to achieve this?

Which complaint request document is created with a mandatory reference to a billing document?

According to the system, there is no stock available; however, you still receive a confirmed schedule line in the sales order.
What is the reason for this confirmation?

You have configured a sales document type with the following number systems:
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Number range internal assignment: 01
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Number range external assignment: 02
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Item number increment: 10
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Subitem increment: 1.
What are the actions and consequences when you create a sales order based on this document type? (Choose two)