AKA Kensington Outline Stitch.
Split Stitch Diagram
Step 1: Bring the needle up at the point labeled 1. Bring the needle down at the point labeled 3.
Step 2: Bring the needle up at the point labeled 2 splitting the stitch previously made. Bring the needle down at the point labeled 4.
Step 3: Bring the needle up at the point labeled 3 splitting the stitch previously made. Bring the needle down at the point labeled 5. Continue in this pattern for the length of the line.
Samples of Split Stitch using 1-6 strands of floss.