# Switching math-mode numerals between serif and sans with the package mathspec

This may be a trite question, but I haven't found an answer and my tentative at it doesn't work. I am trying to set a document in which I use both serif and sans numerals in math mode. I am running the files on top of `XeLaTeX` and using the package `mathspec`. I have the following lines in my preamble (actually, in a class file):

``````\RequirePackage{mathspec}  % This line if in a class or style file
%\usepackage{mathspec}  This one if not in a class or a style file
\defaultfontfeatures{Numbers=OldStyle,Ligatures=TeX}
Everything works except for the fact that digits in the command `\mathsf` are typeset in the serif typeface. I know this is related to having `Digits` in `\setmathsfont`, which selects the serif face, but I cannot remove it without getting the default typeface (cmr) for the numerals in "plain" math mode. If I don't use `\setmathsfont`, I get the default (cmr) for both letters and digits in math mode.