Leading leg on back of needle (Method A)
In this style of left-handed knitting, the leading leg of the stitch rests on the back of the right-hand needle. The knitter inserts the left needle into the stitch on the back of the right needle from left to right and wraps the working yarn *clockwise "over" the left needle. The Purl stitch is executed by inserting the left needle into the stitch on the back of the right needle from back to front and wrapping the working yarn "under" the left needle *counterclockwise.
This results in flat, open knitting in any stitch pattern.
*Perspective for clock orientation in this case means drawing the clock on the screen of the computer and pointing your working needle in the center of it, for knit stitch the point is going into the screen, for purl, the point is coming out of the screen
Leading Leg on front of needle (Method B)
In this style of left-handed knitting, the leading leg of the stitch sits on the front of the right needle. The left needle is inserted from front to back through the front of the stitch on the right hand needle. The working yarn is wrapped *counterclockwise"over" the left needle. For the companion purl stitch the left needle is inserted from left to right through the stitch on the front of the needle. The working yarn is wrapped *clockwise"under" the needle. This results in flat knitting in any stitch pattern.