A GDTI is formed with the following components:
APPLICATION IDENTIFIER (AI): AI (253) to indicate GDTI
GS1 COMPANY PREFIX: A globally unique number allocated to a GS1 member company
DOCUMENT TYPE: The number assigned to identify the type of document
CHECK DIGIT: A modulo-10 check digit used to check for input errors
SERIAL NUMBER: An optional alpha-numeric identification for individual document
The following steps are used to form GDTIs:
Start with your GS1 company prefix
Your GS1 Company Prefix is the globally unique number allocated to your company by GS1 Australia or another GS1 Member Organisation.
Create the document type
The Document Type is a number assigned by you, the holder of the GS1 Company Prefix, to uniquely identify a type of document within your company. The Document Type varies in length as a function of the GS1 Company Prefix length. Note that the combined length of the GS1 Company Prefix and Document Type is always 12 digits.
Hint: Assign your Document Types sequentially, and do not build any intelligence into the number. The scheme that defines a particular document type range as having a set meaning today will mean nothing a short time into the future when your company reorganizes, buys or merges with another firm, or another staff member takes over GDTI assignment duties.
Calculate the check digit
The Check Digit is a calculated one-digit number used to ensure data integrity. Find out how this digit is calculated.
4. (Optional) assign the serial number: The serial number gives you the option of tracking not only specific document types, but also specific instances of each document type (i.e., not just a land registration document, but this specific land registration document). You can assign up to a 17- character alpha-numeric serial number for each GDTI. Again, we recommend assigning serial numbers sequentially, not building any type of intelligence into the serial number itself.