I am new to ERPNext & trying to implement the same in my company. I needed few customized fields in Customer & Supplier forms like PAN No, VAT TIN No. etc. I found that there are two ways to accomplish this task. One was to modify the respective DOCTYPE & other was to use Customize Form. When I used DOCTYPE to add fields, the changes were also visible in Customize Form. But when I made changes in Customize Form, the changes were not visible in DOCTYPE. In both the case the changes were reflected in data entry forms. What is correct & proper way to modify forms ( add / delete / modify fields ) in forms.