There was a good Q/A in the modeling chat about accessing operations from an instance passed as inst_ref. I think it is worth capturing here in the forums so it can be easily found by users who may search xtuml-org.hustlefish-sites.com. Here it is:
dave2: Hi I have a question. If i pass an object to a function using the inst_ref, I am then able to access the attributes of the object by param.