Martin (1992: 521):
And fictional constructions can be broken down into realistic (e.g. romance or detective fiction) and fantastic (e.g. science fiction); in fantastic texts, more has to be constructed as less can be assumed.
 As the meaning of 'realistic' and 'fantastic' suggests, these are ideational distinctions, not textual; that is, field features, not mode features. The confusion is thus metafunctional.
 The use of the word 'texts' here betrays the ongoing confusion between text types (registers) and context (mode). The confusion is thus along two theoretical dimensions simultaneously: stratification (context vs language) and instantiation (system vs instance type).