The suggested length of the unit level UI code is 26 characters and length of aggregated level UI code is 31 characters including time stamp. The serial number for unit level UI and also aggregated level UI is suggested to be made up of nine characters, including numbers, lowercase letters and capital letters. There are two separate sequences, one for unit level UI and one for aggregated level UI. Each product code is made up of four characters consisting of numbers, lowercase letters and capital letters.
Aggregated level UI contains the identifier code of the facility in which the aggregation process took place, which has length of 9 characters for facility codes issued according to the specification. The facility code is made of 5 characters long ID ISSUER prefix and 3 characters long code. ID Issuer generated UIs does not contain time stamp. Time stamp is added by economic operator. More details are given in ID Issuer Technical specification.