[NTG-context] units and decimal separators

Hi ConTeXters, How can I get ConteXt to typeset numbers as it should be done in french in which we use a comma and not a point to separate units and decimals ? That is when I write \mathematics{5,3} I want to have 5,3 and not 5, 3 (with a small space between the comma and the 3), as it is when I use the english separator, a point. Cheers, Seb.