Form code is entered in the customer and then on the work order. (Image below)
The tabs matching this form code and the tabs with no form code and will show on the work order.
You assign the form code to the custom tab (circled in image below). Form codes can be numbers or text.
For example you have a custom tab created for Home Depot customers and you assigned the Form Code of HD. You set the form code on the home depot billing company and every time you create an order for a customer with HD as billing, it sets that form code on the service order and only shows the custom tabs with the HD form code AND any custom tab with a blank form code.