Number On Back Of Stamp - Spain 1905

Hi,

Can anyone help with the significance of the number that I found on the back of this stamp...

A "Control" number
Start at 000,000 and go upwards
000,000 can exist numerous times.

I have read 000,000 referred to specimen stamps
Your Alpha Numeric A814,661 seems very high, never seen one that large.
Both need confirmation
There are lists of numbers out there, somewhere.

SCF "Search" can be your friend
https://goscf.com/t/64563 br /

Thanks Rod. The link given by you got me to another link which says as below (I refer to google translate because I dont know Spanish):

"It can also be noted the existence of very rare specimens with the control number stamped in black, generally indeterminate but more frequently of type A.61x, xxx. The studied set allows us to estimate that its rarity index may be greater than 1000. The stamps of this print were consumed at a rate of approximately 1500 sheets per day."

Link: http://www.filateliaincidental.net/...dete002b.htm

Image:


Does this mean that I have a very rare item here?