There are two “tables” of data available in the BOM report,
AssyData and MasterData. This can be a bit confusing.
MasterData represents fields from the assembly item. AssyData contains
information from the component items and subassemblies. If you expand
MasterData you will see a sub-element, MasterDataAssyData which
represents the component items as linked to the main assembly.
Use AssyData if you want to generate a report that has only information from the component items by themselves.
Use MasterData when you want to generate a report that has assembly information as well as component information. To add component information use the fields found in MasterDataAssyData.