BigFix Inventory Assessment Mechanism

Can someone either provide a quick explanation for or direct me to a place in the doc or website that provides an explanation for … how BigFix Inventory assesses whether a product is deployed on a given endpoint? Does it look for certain file signatures? Does it look for certain executables? Does it look for registry entries? Something else? Thanks in advance.

This should help: https://www.ibm.com/support/knowledgecenter/SSKLLW_9.2.1/com.ibm.bigfix.inventory.doc/Inventory/com.ibm.bigfix.inventory.doc/softinv/r_signature_types.html

Thank you very much!