what if sailmakers don't say actual sailsize? say sailsize 6? one maker makes 6.3 and other 5.8. and later say, its comparable to 6.0 this or that sail? like boardmakers say virtual volume. could be true, one sail more powerful than other, but that is told in description of sail anyway. m2 is m2 and liter is liter, additionally can say feels smaller or bigger. what if someone says board 245 and actual lenght is 239: it feels shorter? it feels wider? virtual lenght width? finally you dont know what you get.all other measures are correct, weight +- 6%, but volume.
buying 1 liter of strong beer, virtual volume 1.5 liters?