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,
+			}),
+		};
+	};
+};