The EPCglobal Tag Data Standard defines the structure of the URI syntax and binary format, as well as the encoding and decoding rules to allow conversion between these representations.
The 'pure identity URI' canonical representation of an EPC is agnostic to the data carrier technology that was used to attach the unique identifier to the individual physical object.
An SGTIN EPC identifier can therefore be constructed by combining the resulting GTIN with a unique serial number and following the encoding rules in the EPCglobal Tag Data Standard.
The EPCglobal Tag Data Standard provides details of the URI prefixes and corresponding binary header values.
Although RFID tags are currently still more expensive than a simple optically readable label, they offer additional capabilities such as the ability to be read by radio waves, without requiring 'line of sight' between the reader or interrogator and the tag; this enables individual items within a large cardboard box (case) to be read without first unpacking each individual item from the box.
Plain text and barcoding are still useful in addition to the EPC tag, as liability obligations for the producer require durable and sufficiently fail-safe labels.
The EPCglobal Tag Data Standard provides details of the URI prefixes and corresponding binary header values.
This namespace indicator (URI prefix or compact binary header value) in turn dictates the length, type and structure of the EPC.