Okay, I know everyone else knows this but I will show my ignorance:
how does one calculate a PFX? It must be adding those three numbers
and not multiplying them, right? Or does one weight the numbers in
some other formula? Maybe it is a diffent thing entirely.

So, could anyone enlighten this old badger?

Oh, I was up in Eureka / Fortuna area this week and found the
Fairyland box. It was in very good shape. Might I comment, echoing
those others who wrote in it, that the instructions might tell one to
turn around at the Immortal Tree and COME BACK 0.2 mi. instead of
continuing past it? That way is a Walter Haas grove. I finally found
a kindly soul in the gift shop who dug out a 1982 map to find the
Abraham Haas grove was back the other way.

The woods there are wonderful. Just like the Forest Moon of Endor
outta Star Wars. Ewoks everywhere. Someone has placed a small charm
in the box echoing the stamp. I left it in there, of course.

Sir Balthazar of 100**100D
P15 F54 X16 L23 D31 RW (redwoods circled aimlessly) 14