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])