The B737 Classic Supplementary Procedures Adverse Weather in the Operations manual states add 10 Knots to VREF if ice formations are observed on the airplane surfaces. A Note states "To prevent increased landing distance due to high airspeed, bleed off the airspeed in excess of VREF + 5 knots+gust correction when below 200 feet AGL. Maintain the gust correction to touchdown.
Disregarding the ice additive for the moment, this brings up an interesting question. The 737 Classic FCTM under Landing Airspeed Control says "..maintain VREF plus the wind additive until approaching the flare." The steady headwind additive is bled off before touchdown while the gust correction is maintained to touchdown.
During a manually flown approach (no icing) where the steady headwind component is high - say 30 knots, so that half the steady HW component is 15 knots, then somewhere on short final steps must be taken to start reducing the airspeed as recommended. From personal observation many pilots hang on to the half the HW component until the flare despite the FCTM advice to bleed off that additive until approaching the flare. This generally results in excessive airspeed which is a no no..
The term "approaching" the flare is therefore rather vague and open to different pilot opinion.
A clue to the Boeing intent ("until approaching the flare") could be the instruction re ice additive of 10 knots to VREF plus the other wind additives where the Supplementary Procedures states: Bleed off the airspeed in excess of VREF + 5 knots+gust correction when below 200 feet AGL.
In other words start the reduction at 200 feet AGL,of half the steady HW. Not wait until the flare itself.