Consider Mr. John Hector, who runs a wholesale stationery shop. When a customer orders various items such as pens, paints, paint brushes, color palettes, and desk supplies from different categories, John raises an invoice in Zoho Books to record the sale. Once the invoice is saved, the custom function is executed to organize the items by their categories and add the category names as headers. For example, items related to art—like paints, paint brushes, and color palettes—are grouped under "Art Supplies." Similarly, other items will be grouped under their respective category headers, and any uncategorized items will be listed under the header "Others". This organized layout helps both John and his customers easily understand the assortment of items on the invoice. 



Note: The Category field will be accessible in Zoho Books after enabling the Zoho Inventory add-ons. 

2. To enable the "Category" field, go to Zoho Books > Items > Field Customization > Hover over the Category field > Click on the dropdown menu and select "Mark as Active".