[NTG-context] Math encoding in XeTeX

Hi, With ConTeXt and pdfTeX you can use \enableregime[utf] (utf8 encoding) with normal mode and math mode (no need to write \pm, \alpha or \times). But with ConTeXt and XeTeX you don't have to specify utf8 regime, because XeTeX can read utf8 directly. However, math mode in XeTeX is a different story ( 256 character tfm's are needed and so, and the encoding has to be ascii, so you have to write \pm, and ± doesn't work). It would be nice if utf8 regime (using uni-xxx files) could be enabled only for math mode when using XeTeX, and so you would be able to input unicode characters in all modes (normal and math). Thanks in advance, Ricard Roca