From the Introduction: Basic d20 assumes that you will use the normal D&D spellcasting system to create characters. Characters will have a number of class-based spellcasting systems to choose from, such as cleric, druid, and wizard. A previous document, Basic d20 Magic Skills, detailed how each school of magic could be made into its own skill, thus eliminating class-based spellcasting entirely. Basic d20 Spellcasting offers an even simpler system: spellcasting based on the generic spellcaster from the SRD.