There's a simple and obviously correct answer to this problem: the markup language should support only standard SI and conversions to weird Angloamerican units should be made from those base units.
The direction of conversion doesn't matter. If a recipe starts out with 300 gr of flour, and that gets converted into 1 3/4 cups + 2 tbsp, that's useless (or at least silly and cumbersome) for an imperial unit user. The whole recipe needs to be recalibrated to use imperial units, and that conversion needs to take culture (I should probably say 'locale', I'm not sure what the right term is here) into account, so that it would use 'sticks of butter' in the US and 'grams of butter' in Australia. I don't think this conversion can be automated.
My point is - recipes cannot be converted easily between unit systems. There is more to converting a recipe than applying a ratio table.
Comments
There's a simple and obviously correct answer to this problem: the markup language should support only standard SI and conversions to weird Angloamerican units should be made from those base units.
The direction of conversion doesn't matter. If a recipe starts out with 300 gr of flour, and that gets converted into 1 3/4 cups + 2 tbsp, that's useless (or at least silly and cumbersome) for an imperial unit user. The whole recipe needs to be recalibrated to use imperial units, and that conversion needs to take culture (I should probably say 'locale', I'm not sure what the right term is here) into account, so that it would use 'sticks of butter' in the US and 'grams of butter' in Australia. I don't think this conversion can be automated.
My point is - recipes cannot be converted easily between unit systems. There is more to converting a recipe than applying a ratio table.