I was looking at the c6 stamps offered on eBay and I came across this listing which has a straight edge with no selvage. I haven't seen this before...can someone tell me the source of this stamp? It is some special sheet or maybe a booklet that I'm not aware of?
Scott C4-6 were printed in sheets of 400 that were cut into panes of 100. They can exist with a straight edge at the top, or bottom, or left, or right, or on two contiguous sides. Like most other straight edged stamps the vast majority have been "improved".