Here's the relevant text to jumping in the BattleMech Manual (most recent source):
A jumping ’Mech can move 1 hex for every available Jumping
MP. Terrain or a hex’s level has no effect on the MP cost: if a hex
is legal to enter, it costs 1 MP to move through or into it. A ’Mech
with at least one Jumping MP may jump down any number of levels.
However, a ’Mech cannot enter a hex with a level higher than the
sum of the ’Mech’s current Jumping MP plus the level of the hex in
which the jump began.
A ’Mech may jump in any direction, regardless of its facing. The
player chooses a hex for the ’Mech to jump to (this may be the same
hex the ’Mech is standing in, costing 1 MP). The ’Mech can only travel to
that hex via the shortest path (i.e. the fewest number of hexes required
to get there), landing with any facing desired. If more than one such
path exists, the player chooses which of these paths their ’Mech takes.
If all such paths are illegal (for example, if there is only one path, and
one of the hexes in the path has a level too high for the ’Mech to enter
via jumping), then the ’Mech cannot jump to the destination hex at all.
And here's the relevant section on jumping and buildings:
Jumping: A ’Mech cannot use Jumping MP to enter a building
hex, though it can enter the hex by jumping onto a building roof).
However, it can use Jumping MP to leave a building hex, provided
it does not enter another building hex other than by its roof at any
point in the rest of the current Movement Phase.
Alright, here comes my (totally stupid question): what prohibition, if any, is there on entering a non-building hex via jumping, if a higher elevation (which is treated as a discrete hex, for stacking purposes at least) overhangs the hex?
To illustrate: let's assume I have a selection of seven hexes in a circular pattern. The perimeter hexes are all level 5 heavy building hexes. The middle hex is woods terrain on the ground level, but after two levels (for the trees, of course), there is a building hex.
I can't find any restriction on falling 'through' a building hex, making a jump from outside the outer hexes into the middle hex (at level 0) a legal maneuver, jump jets permitting.
