This group is so helpfull!
I'm using the free USA album pages from Philosatelia.com (Mr. Blackston). His 2012 Four Flags pages were arranged in rows of 3.
I submitted a request that he make some optional pages with them grouped in rows of 4. He graciously agreed and put the new optional pages on his site. I printed them out and as I was arranging my stamps on the pages I realized that in addition to the 4641-4644 from APU (Avery) that has overall tagging, there is a variety: 4641a-4644a from APU that is on prephosphored paper with a solid tag.
I had all the 4641-4644 overall tag stamps that I had in the old (3 per row) album pages (including all booklet positions). But did not have any of the 4641a-4644a solid tag varieties included on that old style album page. I wondered if I may have had some of the 4641a-4644a solid tagged varieties in my duplicates that I may not have even checked for at the time I was accumulating them.
Sure enough, when I checked my glassines with dupes of 4641-4644 I found several that were solid tagged making them 4641a-4644a.
I even found enough to have solid tagged versions of all the booklet positions except for one. I am lacking the 4644a (Justice) stamp that has a straight edge on both the bottom and right sides.
When I was trying to ID the tagging on the stamps I have, I found, as previously explained earlier in this thread, that the overall tagging has a distinct checkerboard pattern easily visible under some magnification, and the solid tag has, as named, a solid appearance.
I took a couple pics with my cell phone and thought others might like to see the difference side by side so they can check their 4641-4644 dupes too.