Perlfang / Troyer Stitch / Double Stitch

Dear users and authors,
I read something online about Perlfang / Troyer stitch / double stitch. Have you ever tried it?

Hi Josefa, you mean you read about this here on this website, right?
I’m pretty new here and, of course, don’t know my way around very well yet. So please excuse me if I write something wrong.

Perlfang: The term comes from the knitting industry. The knitting yarn is “caught” on certain needles but not knitted. On the side with more visible stitches, i.e. where it wasn’t “caught” but knitted, the stitches look like pearls strung together, hence the name. 
In hand knitting, it’s called “half brioche” or “half patent.” 

Troyer: A sweater with a zipper at the front neckline and a roll collar that can also be left open. It’s often knitted in brioche/patent stitch. I’ve never heard of a “Troyer stitch.” Is that a designer’s creative new coinage?

Double stitch: I know this as a technique for short rows. The turning stitch is pulled up very tightly, making it look like two stitches that are later knitted together and prevent the hole you can get with short rows. Of course, you can also use it for brioche/patent knitting and all techniques with stitches worked into lower rows, because there you also have something like two stitches.
You can even produce quadruple or quintuple stitches if you insert the needle deeply enough!

@Krümelmonster, 
I found these terms online when I was looking for new chat topics for the forum. 
Thanks for your detailed explanations.