Originally Posted by path49

Flagging is when the fabric pushes down into the hole in the needle plate causing skipped stitches. Either because it's clinging to the needle like knits w/lycra will do. Or because it's very thin, lightweight like a lot of silky type fabrics, chiffon, etc.

So, according to the manual, using the far left side of your all-purpose/zigzag foot and the far left side of the plate the fabric has more support....can't pull up with the needle or push down into the hole as easily. Closer to the effect you'd get with a straight stitch foot & straight stitch needle plate.