
230 APPENDIX A
GS1 SGTIN Encoding
The SGTIN is an extension of the GS1 Global Trade Item Number (GTIN) that assigns
Company Prefixes and Item References for use in identifying a particular class of object.
The common 12-digit UPC and 13-digit EAN bar codes are a subset of the GTIN. These
types of codes are being merged with the 14-digit GTIN in 2005 by prepending zeros to the
existing codes. The GTIN doesn’t have an individual item Serial Number, so the SGTIN
appends a Serial Number, the value of which is assigned by the General Manager.
Figure A-1 shows a typical UPC bar code. To convert this UPC into an EPC and store it on
an RFID tag, we must first convert it to a GTIN. This bar code has an Indicator Digit (0), a
Company Prefix (12345), an Item Reference (54322), and a Check Digit (7). To convert
this to a GTIN, we take the entire code as a string and add two zeros to the beginning,
yielding a GTIN of 00012345543227. Notice that our Company Prefix has now become
00012345, an 8-digit number. We will then convert the GTIN to an SGTIN, which allows
us to track individual items, by adding a Serial Number (4208).
To represent a pure identity, the EPC uses a URI expressed in the URN notation. For an
SGTIN, this notation is:
urn:epc:id:sgtin:CompanyPrefix.ItemReference.SerialNumber
This notation includes only the information necessary to tell one item from another; it
does not include the GTIN check ...