It is used to specify, for this entry transaction, the field 'Portuguese VAT' linked to the Portuguese VAT management must be:
The presence or absence of the 'VAT supplier' on the invoice lines also depends on the company parameter valuePORVAT - Portuguese VAT(LOC chapter, POR group) that specifies if the Portuguese VAT is managed or not. If this parameter is set to 'No', the field is not displayed, regardless of the entry transaction setup.