UPC inside line and faking... need help to understand how it works? 1 1

[Coverdeath]

Sorry for the sh*tty title I don't know how to really explain myself...

So on the old comic books I often noticed this line of numbers on the first page near the staples...

 

i was interested by another copy of the same book but I just realized this data isn't present in this one... is these codline not necessary present on each copy? Thanks

[Jayman]

Is it wrapped around the back or on the spine of the second copy?

[Coverdeath]

On 6/22/2024 at 4:11 PM, Jayman said:

Is it wrapped around the back or on the spine of the second copy?

... yes  

Thank you.

However it still an interesting question in overall, are it is necessary always on the books?

[Jayman]

I believe it is just used for the printing process. Perhaps a color code for one of the plates. Placed on the fold of the spine never to be noticed by the consumer unless a bad miswrap.