(Some authors also include non-PG 1159 stars in the class of GW Vir stars.) GW Vir stars may be subdivided into DOV and PNNV stars; they are not, strictly speaking, white dwarfs but pre-white dwarfs which have not yet reached the white dwarf region on the Hertzsprung-Russell diagram.
GW Vir stars encompass a range of celestial objects, including some non-PG 1159 stars. These stars can be classified into subcategories such as DOV and PNNV stars. Notably, GW Vir stars are not white dwarfs but rather precursors to them that have not yet reached the characteristic region on the Hertzsprung-Russell diagram.