Form and meaning
First we need to know what form means and what is its difference from meaning. Form has been used a lot in linguistics by different linguists. It has been used versus meaning or function. It has also been used in Hallidayan linguistic theory versus meaning and substance. But the meaning of form and content in CDA should be to the point.
Linguistic form consists of "phonological/ grammatical/ lexical characteristics of linguistic units, such as sentences, morphemes, lexemes, nouns, etc." (Crystal 2003:185) In Hallidayan linguistic theory models language is comprised of three interdependent levels of form, substance and meaning. Catford believes "language is form not substance" (Catford????:3) that encompasses phonology, graphology, grammar and lexis.