These OCs were made because of what I learned at school, which are noun cases. Nominative (Blue letter N) for subject and predicative name Accusative (Dark Green letter Ac) for complements and circumstances Dative (Orange letter D) for data of an object Genitive (Lime letter G) for possession of an object and... the least used Vocative (purple letter V) for noun inside imperative sentences
NOTE: the color options is from my colored pencils and I'm thinking to add a sixth case
