The whipping thread does not enter the ground material, nor does it go back on itself.
See also the TRC Needles entries on interlaced stitches and threaded stitches.
Examples of a whipped stitch include: whipped running stitch and whipped stem stitch.
Source: THOMAS, Mary (1934). Mary Thomas’s Dictionary of Embroidery Stitches, London: Hodder and Stoughton, p. 42.
GVE