I've been an options trader for 20 years, now I need help on the equity side. In trying to buy and sell stocks the user is presented with numerous exchanges and prices. Some don't fill automatically on the NBBO, others do. Seems like a fun house of smoke and mirrors. Can all ECN's be counted on to fill to their stated size all the time? Here's a beginner's question - how can you tell at a glance which exchange acronyms are ECN's? Does ARCA hit all ECN's? Which exchanges have manual fill environments, as exemplified by the AMEX crime family? Are inverted (crossed) markets always worthless because automated traders would have gotten to it first if it were a real price? In general, when is "what you see is what you get", NOT in effect? If any substantive responder needs help with options, I'll try to answer their option execution questions.