Managed Nav, thanks.
It is interesting that the A320 has a different system to the other types, where Vapp is VLS + a minimum of 5kts (or 1/3 the headwind, whichever is larger to a maximum of VLS + 15kts). Also I take it that the A320 does not reduce the wind component added to Vapp, below 400 feet to 1/3 (the current headwind minus tower reported wind). On 330/340 types a ten knot headwind on the runway would be an addition of 3kts to VLS (albeit minimum to give Vapp = + 5kts), and if at say two hundred feet the headwind was 30 kts then the addition would be (30-10/3)= 7kts onto Vapp. This addition is approximately equivalent to VLS + 1/3 of the current headwind being experienced at the a/c.
Anyhow vive la difference.