Note that this definition doesn't quite distinguish the output of a transformation process from a production process, which is related to the identity/granularity issue.

a produces b if some process that occurs_in a has_output b, where a and b are material entities. Examples: hybridoma cell line produces monoclonal antibody reagent; chondroblast produces avascular GAG-rich matrix.

http://purl.obolibrary.org/obo/IAO_0000125

Melissa Haendel