This paper is a contribution to the discussion about the semantic identity of units functioning as prepositions, verbal prefixes and case suffixes. In an approach inspired by the Theory of Enunciative Operations (Culioli 1990, 1999), the authors consider these kinds of markers as relators which establish an abstract relation of location between two terms X and Y: X is located relative to Y. This idea is illustrated by the analysis of two elements, the verbal prefix and preposition iš in Lithuanian, and the element (t)A of the partitive and elative suffixes in Finnish. The precise nature of the relation set up by iš and (t)A is defined by means of a Schematic Form which enables to account for the various values expressed by these elements independently of their categorial status or contexts of use. Unlike many other approaches to the description of the semantic value of prepositions, verbal prefixes and case suffixes, this paper refuses to postulate the primacy of a concrete meaning over an abstract one, in particular that of space over other fields, even in a historical perspective. The Schematic Form of iš and (t)A is a theoretical tool which makes it possible to account for the ways exteriority is expressed in languages. The four markers analyzed in this paper – the Lithuanian prefix and preposition iš, the Finnish partitive suffix (t)A and elative suffix stA – implement this notion in a specific way, which makes them coincide locally but only on a limited overlap: each marker has an identity which is specific and cannot be assimilated to that of the other.