This paper presents a unified account of the meaning of the spatial relational terms right, left, in front of, behind, above and below. It claims that each term has three types of meanings, basic, deictic and intrinsic, and that the definitions of each type of meaning are identical in form for all six terms. Restrictions on the use of the terms, which are different for above and below than for the rest, are explained by a general constraint on all uses (...) of spatial relational terms, the framework vertical constraint. This constraint depends on the existence of a fourth type of meaning for above and below, one defined by the framework in which the related objects are located. It is argued that a theory centred on the framework vertical constraint is preferable to one centred on the principle of canonical orientation (Levelt, 1984). (shrink)