We present a unifying, consistent, finite-size-scaling picture for
percolation theory bringing it into the framework of a general,
renormalization-group-based, scaling scheme for systems above their upper
critical dimensions dc. Behaviour at the critical point is non-universal in
d>dc=6 dimensions. Proliferation of the largest clusters, with fractal
dimension 4, is associated with the breakdown of hyperscaling there when free
boundary conditions are used. But when the boundary conditions are periodic,
the maximal clusters have dimension D=2d/3, and obey random-graph
asymptotics. Universality is instead manifest at the pseudocritical point,
where the failure of hyperscaling in its traditional form is universally
associated with random-graph-type asymptotics for critical cluster sizes,
independent of boundary conditions.Comment: Revised version, 26 pages, no figure