Add the Attribute item data model

module/data/Item/attribute.mjs

@@ -0,0 +1,35 @@
+export class AttributeItemData extends foundry.abstract.TypeDataModel {
+	static defineSchema() {
+		const fields = foundry.data.fields;
+		return {
+			group: new fields.StringField({
+				blank: false,
+				trim: true,
+				nullable: true,
+				initial: null,
+			}),
+			key: new fields.StringField({
+				blank: false,
+				trim: true,
+				nullable: true,
+				initial: null,
+			}),
+			aboveTheFold: new fields.BooleanField({
+				initial: false,
+			}),
+
+			/* The attributes current value */
+			value: new fields.NumberField({
+				integer: true,
+			}),
+			/* The minimum accepted value */
+			min: new fields.NumberField({
+				integer: true,
+			}),
+			/* The maximum accepted value */
+			max: new fields.NumberField({
+				integer: true,
+			}),
+		};
+	};
+};

module/hooks/init.mjs

@@ -5,6 +5,7 @@ import { PlayerSheet } from "../apps/PlayerSheet.mjs";
 import { SingleModePlayerSheet } from "../apps/SingleModePlayerSheet.mjs";
 
 // Data Models
+import { AttributeItemData } from "../data/Item/attribute.mjs";
 import { GenericItemData } from "../data/Item/generic.mjs";
 import { PlayerData } from "../data/Actor/player.mjs";
 
@@ -35,6 +36,7 @@ Hooks.on(`init`, () => {
 	// #region Data Models
 	CONFIG.Actor.dataModels.player = PlayerData;
 	CONFIG.Item.dataModels.generic = GenericItemData;
+	CONFIG.Item.dataModels.attribute = AttributeItemData;
 	// #endregion Data Models
 
 	// #region Sheets
@@ -61,6 +63,7 @@ Hooks.on(`init`, () => {
 		__ID__,
 		GenericItemSheet,
 		{
+			types: [`generic`],
 			makeDefault: true,
 			label: `taf.sheet-names.GenericItemSheet`,
 		},