This type of SF is, it would seem, derived from the previous types through a process of copying and conventionalisation.    From Wordnik.com.  [Archive 2005-12-01] Reference

This novum is not the same thing as a genre trope, not at all -- though most novum will eventually be recycled by later writers, and a set of tropes derived from the process of conventionalisation, symbolic formulation.    From Wordnik.com.  [Archive 2006-07-01] Reference