Invoice Number in Sales Invoice Form is automatically generated and it is in sequence. When you press “New Invoice Button”, then all the columns on left pane area are automatically filled and cursor automatically goes to right table area in the “Item Code” column.
In the Purchase Invoice, the Invoice No. and date columns are not automatically filled when you press “New Invoice” button. Because unlike sales invoice, purchase invoice numbering is not your own choice. You will write the number as appears on actual purchase bill.
Similarly, in cash book also, the voucher number column is not automatically filled. You will write the actual bill number, deposit slip number, withdrawal cheque number etc.
In the sale return/purchase return forms, you will write the original sale invoice number plus original date/original purchase invoice number plus original date.