When I worked for SIAC, the IT subsidiary of NYSE/AMEX, we used to keep an MVT Abend Dump around to use when interviewing prospective programmers and Systems Programmers.
We’d hand the dump to prospects and wait for their reaction. The guys who said, “The program bombed”, without looking deeper were immediately crossed off our list. We finally interviewed a guy who spent 10 minutes examining the code and scratching his head before admitting, “I can’t figure it out. It’s impossible. That failure couldn’t have been caused by that instruction”.