https://images.app.goo.gl/kTswwMCbzfbWi3gN6

https://images.app.goo.gl/w42HjjYV9Ajuiyyr6


I have attached a URL please have a look. First one is allowed region for L and D residue

Second one state the quadrant numbering

Quadrant nomenclature or numbering of ramachandran plot is same as Cartesian coordinate