Complex sentence: Group RGT (or sometimes Group R-GT), is a FIA specification for GT cars in rallying, as described in Appendix J, article 256 of the FIA sporting regulations.
Split into simpler sentences: Group RGT (or sometimes Group R-GT), is a FIA specification for GT cars in rallying. The technical regulations are described in Appendix J, article 256 of the FIA sporting regulations.