First-order projection-based binding-time analysis has proven genuinely useful in partial evaluation Lau91a, Lau91c]. There have been three notable generalisations of projection-based analysis to higher order. The rst lacked a formal basis Mog89] the second used structures strictly more general that projections, namely partial equivalence relations (PERs) HS91] the third involved a complex construction that gave rise to impractically large abstract domains Dav93]. This paper presents a technique free of these shortcomings: it is simple, entirely projection-based, satises a formal correctness condition, and gives rise to reasonll abstract domains. Though the technique is cast in terms of projections, there is also an interpretation in terms of PERs. The principal limitation of the technique is the restriction to monomorphic typing.