Scott 634d Booklet Pane On Cover?

So just trying to determine if this would be considered a full booklet pane on cover even though it is separated into 3 sections. Or would it need the top selvage as well as being intact?

It's not a booklet pane unless it is intact just as a block or sheet is neither once disassembled. They can be reconstructed but that is not the same.

thanks rogdcam!

I think that question has never been addressed fully.
Your cover could be considered "The next best thing to a booklet pane on cover". A ranking, top to bottom of "value", would go like:

1. Full booklet pane with tab
2. Full booklet pane but without tab
3. Blocks/pairs of stamps forming a booklet pane of 6
4. Blocks/pairs of stamps forming a partial booklet pane
5. A single pair of stamps from a booklet pane
6. A single stamp from a booklet pane

As you go back in time, you'll also go down the ranking ladder. For modern booklet issues, it is not too difficult to find letters having complete panes (with some exceptions, like for example the first setenant issue, the 6c/18c pane which is difficult to find on cover as a complete pane). For the very early booklet issues, full panes are extremely rare which shows in the catalog values. Note that the panes must be cancelled in the period usually assigned "contemporary", meaning the letter should be postmarked before the next booklet stamp issue was introduced.
Some early panes were on sale for rather short periods which also makes it more likely few "top ranked" letters (still) exist. Most "used-on-cover-booklet pane collectors" (the few that still exist is my guess) are therefore happy having a booklet pair on a letter from the first few issues. Booklet pairs make it more easy than a single stamp with straight edge which could also be an ordinary sheet margin stamp.

In the case of the 634d issue, it was printed in masses so there are some letters with full panes that survived, and lots of letters with blocks/pairs. Your example is absolutely collectible as "the n ext best thing". A postage rate of 12c was high at the time so it required some creative rates, like a special delivery envelope. Most letter probably show a 10c W/F and a 2c W/F stamp, a letter marked with booklet stamps only is unusual.

Also, full booklet panes usually required a rather large envelope to fit the complete pane on it, so many panes were broken up like the one you show. The suspicion also lingers that many covers with full panes with tabs (like fdc covers) may be philatelic in nature.

Here's an example of a late use of a full 634d pane (image from ebay):

Nice ranking ladder, drkohler. Echoing a topic from another thread, how much does a philatelic cover cause a drop down the ladder? The cover you posted being a late-use philatelic cover, it would certainly fall below the top-ranked non-philatelic cover with full tab. Would it even drop below the non-philatelic cover without tab? In other words, is the philatelic cover with tab more, or less, collectible than the same complete pane on a non-philatelic cover without tab?

Individual collectors may have a strong preference for one over the other, but is there a general consensus?

I have some modernish booklet panes off-cover with first day cancels. Should they be valued around the same price as a used booklet pane, or significantly less because they are philatelic?

Modern full panes with fdc cancels, removed from the covers, are essentially worthless. That sounds brutal but is more or less the consensus amongst booklet collectors. Then we have panes still on fdc covers that were actually mailed, here the jury is still out I'd guess. But my hunch is such panes would value less than full panes on a commercial cover.

As a general rule, full booklet panes on letters should stay on letters. In the far future, if collectors are still around, these will be uncommon (as most modern stamps wander into the trash can nowadays).

The "contemporary rule" is important because it is no problem to now buy an uncanceled/"unpretty" 300b pane, glue it to a cover and mail it. You'd have a genuine used 300b pane, but it won't make you rich as it "doesn't count".

The full pane 634d letter from 1933 above "does count" as a genuine use. Although the next booklet issue was issued in 1932, that was a 3c stamp (Washington Stuart) issue so technically the 634d contemporary use lasted into the early 1940s when the 1c, 2c, 3c presidential panes were issued.

It is a slippery slope when "contemporary use" uses its validity, "Late use" is still acceptable as a genuine use, and "Philatelically irrelevant" takes over.