Printronix SL4M Reference Manual page 104

Chapter 3
Splitting the EPC
When the customer chose 36250103 as the MSB 64 bits, the
leading zeros were padded to the left until 64 bits were filled,
resulting in 00000000036250103. This converted to hex so that
00000000022921F7 was written into those bits.
This means the full number (minus the insignificant leading zeros)
was hex 22921F700000455 (decimal 155693006861632597),
which is not the number the customer meant.
Simplest Solution
Use the 32 bits first, let it hold the leading zeros, then set the 64 bit
to the desired decimal number.
NOTE: This will only work for numbers less then decimal
Example
RFWTAG;96
32;D;*0 *
64;D;*362501031109*
STOP
For numbers greater than this, care must be taken to split the
number in the correct fashion. The easiest method is to use hex (or
at least convert to hex and then back again into decimal).
104
18446744073709551615 (hex FFFFFFFFFFFFFFFF).