Something is wrong in the current implmentation of \tfrac. If we take away all the bells and whistles provided by \definemathfraction, * \tfrac#1#2 should be equal to {\textstyle #2 \over #1} * \dfrac#1#2 should be equal to {\displaystyle #2 \over #1} * \frac should be equal to \tfrac in inline math and \dfrac in display math. In the current implmentation \frac works correctly, but \tfrac does not. For example: \startbuffer \frac 12 \tfrac 12 \dfrac 12 \stopbuffer \starttext $\getbuffer$ \startformula \getbuffer \stopformula \stoptext The output of \frac and \dfrac is correct in both inline and display mode. The output of \tfrac is wrong in both modes. In both modes, \tfrac should equal the current output of \frac in inline mode. Although I don't completely understand the code, my guess is that there is a bug in how mathstyle=text is implemented (really, mathstyle=text should be equivalent to mathstyle=empty in inline math mode). Thanks, Aditya