Halliday & Matthiessen (1999: 416):
The two orientations towards meaning thus differ externally in what disciplines they recognise as models. These external differences are associated with internal differences as well.
First, the orientations differ with respect to where they locate meaning in relation to the stratal interpretation of language:(a) intra-stratal: meaning is seen as immanent — something that is constructed in, and so is part of, language itself. The immanent interpretation of meaning is characteristic of the rhetorical-ethnographic orientation, including our own approach.(b) extra-stratal: meaning is seen as transcendent — something that lies outside the limits of language. The transcendent interpretation of meaning is characteristic of the logico-philosophical orientation.