In Systemic Functional Grammar, language is seen as a social system of semiotic resources, which exists as a meaning potential.  The system is organised into 'strata' at different levels of abstraction.  They are related by means of realization.  The semantic strata is realised in lexicogrammar - the network of lexical and grammatical options available for the expression of meaning. In the semantic strata, three basic elements of a semantic configuration are identified: process, participant and circumstance.  These are realised in lexicogrammar as verbs, nominals and adverbials.  CDA is often concerned with transitivity choices at the level of lexicogrammar.   The availability of choice in lexicogrammar means linguistic representation is always necessarily ideological.