On my Bernina it is the number 4 stitch.
Also called the Running Stitch.
I am a big fan of straight line quilting
and this just gives the straight line a little pinache!
I am using it today on a "Sew Together Bag"
To use this stitch I put my walking foot on my machine.
Set stitch length to between 2 and 2.5
and set the width to as wide as it will go.
Then just sew back and forth across your project.
Nice little squiggle lines..... Love the texture.
Try it on a small project. It may just become one of your fav's.