Magic Accuracy is a concept in Final Fantasy XI. Generally speaking, magical accuracy is a hidden stat that determines the likelihood any spell will land on its target (provided the target is not specifically immune) without being fully or partially resisted. Magical accuracy is calculated using different stats and skills for different spells.
White Magic is adjusted by Mind; Black Magic and Ninjutsu are modified by Intelligence; Songs are modified by Charisma and Blue Magic can be modified by any statistic (specific to the spell being cast).
Depending on the type of spell, the majority of the magical accuracy will be determined by Elemental Magic, Enfeebling Magic, Healing Magic, Divine Magic, Ninjutsu, stringed instrument or wind instrument, or Blue Magic skill.