about EAM integration with INV, how to define if an asset is located in sub inventory ro not?

hi guru:

recently i noticed there is a sub-inventory column in asset number form, and when i using the asset move workbench, i also noticed it support for transfering  assets not in subinventory, so here is my question, how to define if an asset is in subinventory or not, and how to understand the concept of subinventory from the perspective of EAM module?

thanks in advance!