[Legendary League]

In regards to NAPs, they typically follow the length and duration that matty has outlined (but you can certainly create an NAP following what Vanguard has proposed, but you'd need to outline that specifically). NAPs however are just one diplomatic tool at your disposal, and in most games where diplomacy isn't rigidly enforced, you have quite alot of leeway in your dealings (esp. in regards to interstate relations). Maintaining an NAP is always well and good (particularly if you keep a reputation for honoring them), but players often tend to be overly blinded by them into extending them to a point where it is detrimental to their own position. A reverse prisoner's dilemma, if you will. This has happened to me in my first MP games, to the point where I played completely reactively (even in no diplo games). I'm moving myself into a more proactive mindset, but that's the pitfall of relying on NAPs overly much.

As for what an NAP means in terms of limitations, well. I personally feel it's limited to direct (and blatant indirect) aggression. There is only one winner at the end of the game, so sending in spies and scouts into enemy territory to scout is perfectly acceptable. It's also perfectly acceptable to instill uprisings, up until you're caught. Similarly, it is possible to use Hurricanes against an NAP'd nation if there are four nations who can cast it, and have reason to do so against said nation; in which case plausible deniability can come into play (i.e., who really sent the hurricane, and how do they know which provinces to target?]). If the enemy nation has hidden thugs in all your provinces in preparation for an alpha strike (for the expiration of an NAP), that too is acceptable so long as they aren't discovered. I also feel the same way about diplomacy with other nations regarding NAP partner (that is, it is perfectly valid to share intelligence, raise suspicions, and to form coalitions against an NAP partner, or to aid their enemies through trades, etc., provided you yourself do not undertake direct aggressive actions against NAP'd nation). Ultimately, NAPs are signed to further the purpose of a nation: in that case, it is to prevent aggressive attacks or moves against your nation from a neighbor, and to buy time from that front as you build up your own base of power.

Signers of NAPs do so under the knowledge that the NAP is not permanent, and will be cancelled eventually (and both nations will come into conflict, if they survive).

Now I personally don't go to these lengths (and indeed, hold my actions to a very high standard of non-aggression), but that is in my opinion the fundamental limits of an NAP. You can certainly define the NAP in more detailed format to cover these bases, of course, and to delineate what is considered aggressive behavior confined by an NAP (blood sacrifices on the border, for example, can definitely be considered such an action, whilst hidden thugs preparing to alpha strike aren't, because the first has malicious intent, is blatant, and is clearly aggressive action undertaken during the NAP, whilst the latter is also malicious, but is nominally stealthy and is maneuvering to prepare for an aggressive strike after the NAP expires).