Hi Michael,
Well I have a confession. I am more like you than you know. I too got interested in "airliner" type flying a while back and even though I'm programming it, I haven't fully mastered it, I still have a lot to learn. What I have learned though during my research of FMC / CDU operation, is:
1) you'd be surprised how many people aren't exactly sure how things work when recalling it from memory and
2) there are indeed small deltas to how the FMC operates between software version and some folks never quite get to see the alternative operation and so get quite dogmatic on how its supposed to work, when in reality, there are variations.
I have two very comprehensive FMC manuals and they simply do not give the 'minimum criteria' for the EXEC lit to be lit....at least not that I have been able to find. All examples given in these references have you to press the EXEC key while some waypoints are loaded. So...that being said, I think you have indeed found a bug in the tutorial document. I can only guess that we might have taken a screenshot of the PERF INIT page while some waypoints were loaded and we just didn't catch it.
Philosophically, I see no reason the EXEC light couldn't light up after entering some PERF INIT data without a route (at least 1 waypoint), after all, its just a way to tell the FMC "do some calculations now"....and with only PERF INIT data entered, any calculations without the route would be minimal....there are a few, but nothing that alters the flight path of the aircraft. One of my (quite official) FMC texts uses the phraseology,
It could be argued that PERF DATA without a waypoint cannot be a flight, and therefore is not a flight plan....nor is PERF DATA only a guideance mode or part of the navigation database. I think this was the logic I used when programming it originally. If you have at least one waypoint (from the navigation database), then you have a minimal flight and that's when you get the EXEC light (after ACTIVATION).
More confusing to me still is the term ACTIVATE. For example, below is some text from my rather official FMC manual I have.
The above says that entries have been activated by pressing the lighted EXEC key; however, we all know that before hitting EXEC for the first time, there are the words ACTIVATE on LSK 6R...which must be pressed before EXEC. So.... if, according the manufacturers own manual, 'activated' results from pressing the lighted EXEC key, what the heck are we activating when we press ACTIVATE? I tell ya, communication is a finicky thing!
Anyhow, thanks for catching that, we'll make the appropriate updates and I hope you don't get too discouraged. Learning an airliner and the ins and outs is daunting and I myself have a long way to go, usually I only undestand one thing at a time and right now, its holds!
Thx again,
TomK