maplestation_modules/code/modules/client/preferences/spellbook/spellbook_item_customization_menu.dm

/datum/spellbook_customization_entry	NOT SERIALIZED - The data provided by these entries are instead extracted and serialized into lists of (string -> any) values, that are then associated in the spellbook preference as (item.type -> list).
/datum/spellbook_item_customization_menu	The TGUI manager for the spellbook item customization menu.