Generally, I agree with poobaloo's interpretations.
Maslow and I did go back to the rulebook. Maslow pointed out the rule stating "An Army can be ordered to move into an adjacent inland or coastal province" and also "An Army can move across water provinces from one coastal province to another via one or more Fleets." Therefore, by definition, a unit can not be ordered to move from Belgium to Paris (*if* one assumes that the above rules are 100% complete... which is a matter of interpretation).
I countered with the rules stating when a support can be given. The emphasis is on whether a unit is ordered to move or not. And this left me with the same question that Garry asked: Can a unit ordered to move *invalidly* receive support to hold? Is it trying to move? Or does its invalidity make it a holding unit? In fact, I referred to Garry's House Rules in the context of the discussion
In Maslow's interpretation, since invalid orders are, by definition, not allowed, then any invalidly ordered unit reverts to: "Not giving a unit an order is interpreted as ordering it to hold."
This is, by the way, how I interpret invalid orders. Still, what has been missing is an overt statement in the rules that an invalid movement order becomes an order to hold.
Mike Sims cited the following rule: "Any vague or invalid orders are ignored." Unfortunately... that rule appears in a section entitled "Writing Build and Disbandments". It clearly refers specifically to adjustments. There is not a complementary rule for movement orders.
In short... I see no clear correct answer.
Myself, I think that the general practice of "Invalid orders become orders to hold" takes precedence, and I would adjudicate as though all such units were ordered from the outset to hold.
Note: this is *not* how RP works. Or the judges. They will treat an invalid movement order as an attempt to move.
Like others, I agree that the really tricky scenario was A Bel-NAf. The rules say:
"If Fleets occupy adjacent water provinces, an Army can be convoyed through all these water provinces on one turn, landing in a coastal province adjacent to the final Fleet in the chain."
I would argue that, since there is not an unbroken chain of fleets running from Belgium to NAf, the army's order is invalid and should be treated as A Bel Holds.
A final thought: I have never encountered any of these scenarios in a real game. (And I hope that I never do).
Adam