In this paper we propose several formal tools intended to grasp an important aspect of static localisation in language namely orientation. We consider French spatial expressions used in localising an entity in an internal way (Internal Localisation Nouns such as 'haut' (top), 'bas' (bottom), 'devant' (front), 'derrière' (back)) or in an external way (prepositions 'devant' (in front of), 'derrière' (behind), 'au-dessus de' (above), 'au-dessous de' (below)). In order to represent these orientation phenomena, we build a logical framework made up of three levels that we call geometrical, functional and pragmatic. First, we define a geometry based on directions and relative localisation operators. Then, we introduce the functional notions that underly intrinsic orientation processes and we propose several formal definitions which may serve to represent the semantic content of the studied lexemes. These definitions allow us to make a difference between deictic and intrinsic uses of these spatial expressions and to draw interesting deductions and inferences. Finally, we integrate at the pragmatic level various principles governing the interpretation of such orientational expressions. By taking into account the different inferential schemata linked to the use of spatial expressions in discourse, this modular approach constitutes an original contribution to the semantic and cognitive studies of linguistic space.