Teun A. van Dijk and Janos S. Petofi. Walter de Gruyter, 1977. Instead, he views sentences as realizing text rather than constituting it. Halliday also views text as a projection of meaning at a higher level. He argues that the answer depends on one's perspective, the nature of the enquiry and the ideology of the enquirer, for there are different higher level semiotics and often different levels of meaning within each of them.
Literary texts are an example.
A text is also the realization of higher level semiotic structures that have their own modes of interpretation, literary, sociological, psychoanalytic, etc. Text for Halliday is a product of its environment and functions in that environment. The individual member is, by virture of his membership, a 'meaner,' one who means. By his acts of meaning, and those of other individual meaners, the social reality is created, maintained in good order, and continuously shaped and modified. To attempt to encapsulate Halliday's functional perspective regarding text and environment in summary or abstract form is to detract from the elegancy of his argument, the depth of his own understanding and vision of text as continuous process, and the constantly shifting reltionship between a text and its environment and culture.