When the Supplier is Greek, the Invoice Id second segment must be a valid Date that matches the invoice Issue Date
/ubl-invoice:Invoice/cbc:ID[$isGreekSender] | /ubl-creditnote:CreditNote/cbc:ID[$isGreekSender]string-length(normalize-space($IdSegments[2]))>0                                   and matches($IdSegments[2],$dateRegExp)                                  and ($tokenizedIdDate[1] = $tokenizedUblIssueDate[3]                                     and $tokenizedIdDate[2] = $tokenizedUblIssueDate[2]                                    and $tokenizedIdDate[3] = $tokenizedUblIssueDate[1])