Halliday & Matthiessen (1999: 572):
As designed semiotic systems emerge, both the registers of the everyday language and the original specialist registers continue to exist and develop; folk models of the world will co-exist along the scientific ones. A certain degree of intertranslatability is likely to be maintained — linguistic renderings of logical or mathematical formulas, for instance; and this constitutes one of the contexts in which ordinary language is brought into explicit contact with more scientific varieties.