N.C. pins, Not Connect pins

It looks conflicting/complicated because there are different families and different use cases.

For example, take from the Stratix III guidelines you quoted. It may sound complicated but it really comes down to this:

In a given package there are some pins that will be NC (not connected do the die) in some devices but in bigger devices will be connected to the die (Vcc, GND, VREF, etc).

The guidelines say that if you're don't intent to migrate to a bigger device, you SHOULD (not MUST) leva NCs unconnected.

However, if you intent to migrate to a bigger device, you MUST connect those pins properly.

On the other hand, the MAX V guidelines FCORDOBES quoted say you MUST leave NC pins unconnected. It's a stronger statement that the one in the Stratix III guidelines but different families have different guidelines.

And I think none of MAX V packages actually has NC pins...

The .pin report is, however, case specific.

For your combination of device family, package, intended migration devices, unused pin options, etc, it will tell you exactly what pin will be for your case.

Which only leaves one question: what to do with the NC pins that show up in the .pin report?

There isn't nice guideline document for older families like MAX3000, but you can leave them floating.