Does This Count As Imperf Between?

Not if it's a straddle pane copy, which it probably is.

hmm, is there a way I can remove the "probably" from it being a straddle pane? Or is there not enough stamp to eliminate the doubt?

I searched "straddle pane", but no luck in finding an explanation how to identify it.

I am not sure if you can definitively say whether it is a straddle margin copy by measuring the spacing or not. Even if you could prove that it isn't a straddle margin copy, you need to have a pair of stamps to prove that an unusually large margin has not been trimmed off.

On the 1857's, the perfs were frequently so far off that scissors were used to separate the stamps, giving the appearance of imperf between.

I have some horizontal multiples. Some measure 5mm between stamps (as the one above does), some measure 6mm between. Is the measurement between panes, equal to the measurement between stamps?
Sinclair2010, I believe your second post is the "wet blanket" in this case.
My example is centered way left. I can imagine perfs being on the right running through the adjoining stamp.

dudley and sinclair2010, as always...thanks.

You must have meant that you can't imagine perfs on the right running through the adjoining stamp?

I don't really think that is the case, though it could be. I am just saying that lots of things happen and there are lots of possibilities. It is difficult to impossible to eliminate all of the could be's and the what if's when it comes to single stamps.

Although I do not think it is a straddle stamp, here is an example of a wide margin Bank Note that I have. Winston is right, I do not think that a single stamp like your example could ever get a cert as an 'imperf', sorry.
Don

Don, alas...at this point I figured as much.
The fact that it's in this lot of #158's and I was able to purchased it, was the first clue.

Although not a Bank Note issue, one that similar.