Sweden Stamp Varieties According To Facit: What Are Plåtsår And Plåtskarvtecken?

I recently got a FACIT Special Classic 2022, but I was unsure what some of the terms mean, even though the catalog is in Swedish/English.

Do either plåtsår or plåtskarvtecken refer to the coil lines that appear on Swedish stamp of the early 1900s (similar to coil lines on US stamps)?

I see the that both of those terms warrant a premium according to the catalog. For plåtsår, FACIT translates it as plate scar, and plåtskarvtecken is translated as plate join signs.

The catalog mentions as part of plate joining about dots and numbers in margins where plates were joined, that sometimes appear on stamps that are miscut. These digits/dots may be what plåtskarvtecken refers to, but I'm unsure if the coil lines fall under that too.

I could see that the coil lines might not fall under that term, because they might not deserve much of a premium, as the lines would appear all through a sheet of stamps.

I could see that the digits/dots COULD have a premium, because they would only appear once or twice per sheet, on outer margin.

Surely though, the coil line must have some extra value, even if it's small, as the coil line only appears every 17 stamps? Maybe they're still common enough that there's no extra value...

I feel like I almost answered my own question, but I'd appreciate input from someone who knows a lot better than I do!

Here is an example of plåtskarvtecken:




(not mine)

I don't know how much needs to show to be desirable to specialists, but I assume more is better?

I believe the plåtskar denotes just the joint lines, as in your examples. The plåtskarvtecken have portions of numbers or letters included, and typically also mean the coil is off center enough for it to appear.

OK,

Thank you for the information Cjd and billsey! Googling was not very helpful.
(Sorry about the late response. I thought I'd subscribed to the topic, but must not have, as I never received a notification about replies.)

Is plåtskar the same as plåtsår?
My FACIT mentions in the catalogue listing of varieties: plåtsår (translated as plate scar) and plåtskarvtecken (translated as plate join signs) as well as plåtspricka (translated as plate crack), but no mention of a variety called just plåtskar.

Also, if plåtskar/plåtsår is the joint lines, why does the variety not appear if every coil stamp listing, if every listing should have joint lines?
For example, the 35 ore stamp on the left in my picture (FACIT 187, Scott # 181) has no plåtskar/plåtsår listing under it, though the picture shows that it definitely exists?