Printronix SL5000r MP - Manual (Page 73)

Class 1 Gen 1
73
64 Bit And 96 Bit EPC Data Formats
According to the EPC code standard there are two specific data
type formats: 64 bit and 96 bit. The type of format is defined by the
first two bits of the EPC Header. When the first two bits are set to
00, the EPC format is interpreted as a 96 bit data format. When the
first two bits are not 00, the EPC format is interpreted as a 64 bit
data format.
Each tag class handles this situation differently.
Class 1 Gen 1
The original Class 1 Gen 1 tag was a 64 bit memory designed prior
to the EPC standard. Therefore despite a newer 96 bit tag, the data
dependent indication was ignored. This is true today and therefore
as long as the data fits into the tag memory no check is made of its
format.
Gen 2
The Gen 2 protocol manages data size differently and does not use
the data format to identify the data size. The Protocol Control (PC)
bits (a separate entry in the tag) manages the data size. Therefore
the data format is not restricted to the EPC data format.
Class 0+, Class Zuma, and Class 1.19
These Classes were developed subsequent to the EPC standard
and have 96 bit memories for the EPC code. To distinguish
between 64 bit data and 96 bit data, they conform to the EPC code
format standard.
Three parameters should match for error free operation:
1. EPC Format
2. Selected Tag Data Length
3. Size of Data Request