what is the significance of the ", 0," in the "pack('NN', 0, $_)" statement?

The value for the first "N". 

Q=654848
-----------------------
00 00 00 00 00 09 fe 00
----------- -----------
N=0         N=654848

[download]

I also need to pad the above value with two spaces, i.e., "00 00 00 00 00 09 fe 00 20 20"

More concisely, you want to add two spaces. pack: 

C  An unsigned char (octet) value.
A  A text (ASCII) string, will be space padded.

[download]
pack('NN CC', 0, $_, ord(' '), ord(' '))
pack('NN CC', 0, $_, 0x20, 0x20)
pack('NN A2', 0, $_, '  ')
pack('NN n',  0, $_, 0x2020)

[download]

In reply to Re^3: zero fill with pack by ikegami
in thread zero fill with pack by Spooky

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