Lines In Margin. Gutter Snipe?

I thought, lines showing in the margins, were called gutter snipe. But after some searching, I don't believe that's correct. Just plate gouges then?

These are not "gutter snipes". A gutter snipe occurs when the pane is improperly cut leaving the entire gutter and occasionally a portion of the adjoining stamp and perforations. A guttersnipe should be regarded as an "error", whereas gutter blocks and pairs are the naturally occurring result of leaving the sheet intact.

My first thought was plate end impressions.

Hal

Those lines are Pane Divider lines. It is the mark put there to guide the worker to cut along that "arrow" when he cut up the sheet of 200 stamps into two panes of 100 stamps. Both of these are position 1R (first stamp, right pane) on the sheet. The straightedge at left is "natural" and not considered a "fault". In fact, pane divider copies such as these are generally considered premium items by specialists.

These pane divider lines ceased to exist at some point (my guess is in the c.1890s period) so they can only be found (if I am correct) on pre-c.1880s stamps. Perhaps one of the other "experts" here will know exactly when they stopped.