A material BOM is a list of components that make up a material. It can be used to describe the structure and composition of a product or a spare part. A material BOM can be assigned to one or more technical objects, such as equipment or functional locations, to define the materials required for maintenance activities1.

One way to assign a material BOM to a piece of equipment is via the field construction type in the equipment master. The construction type is a material number that identifies the material BOM for the equipment. By entering the construction type in the equipment master, the system automatically assigns the material BOM to the equipment2.

The other options are incorrect because:

Via field model number in the equipment master: The model number is a material number that identifies the material of the equipment itself, not the material BOM. It is used to create an equipment BOM, which is a list of components that are installed on the equipment. An equipment BOM can be different from a material BOM, as it can reflect the actual configuration of the equipment2.

Via material BOM header in the serialization data: The serialization data is a view in the material master that contains information about the serial numbers of the material. It is not related to the material BOM or the equipment assignment3.

Via creation of an equipment BOM: The creation of an equipment BOM is a different process from the assignment of a material BOM. An equipment BOM can be created from a material BOM, but it does not automatically assign the material BOM to the equipment. An equipment BOM can also be created manually or copied from another equipment2.

References: 1: Using Bills of Materials (BOMs) - SAP Learning 2: SAP PM Bills of Material Tutorial - Free SAP PM Training - ERProof 3: Serialization Data (SAP Library - Material Master (LO-MD-MM))