Hello! Some days ago, I asked about how to use sans serifed font in all math document. My approach, given those answers, was create a little function to use the serif fonts in math (using \definestartstop) but, when there is some align involved, it produces an error :-\ . An example is the following: %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% \definefontfamily [mainface] [ss] [Latin Modern Sans] \definefallbackfamily [mainface] [mm] [Latin Modern Sans] [preset=math:digitsnormal] \definefallbackfamily [mainface] [mm] [Latin Modern Sans] [preset=math:digitsbold] \definefallbackfamily [mainface] [mm] [Latin Modern Sans] [preset=math:uppercasenormal] \definefallbackfamily [mainface] [mm] [Latin Modern Sans] [preset=math:uppercaseitalic] \definefallbackfamily [mainface] [mm] [Latin Modern Sans] [preset=math:uppercasebold] \definefallbackfamily [mainface] [mm] [Latin Modern Sans] [preset=math:uppercasebolditalic] \definefallbackfamily [mainface] [mm] [Latin Modern Sans] [preset=math:lowercasenormal] \definefallbackfamily [mainface] [mm] [Latin Modern Sans] [preset=math:lowercaseitalic] \definefallbackfamily [mainface] [mm] [Latin Modern Sans] [preset=math:lowercasebold] \definefallbackfamily [mainface] [mm] [Latin Modern Sans] [preset=math:lowercasebolditalic] \definefontfamily [mainface] [mm] [Latin Modern Math] \definestartstop [formulass] [ before={\startformula \setupbodyfont[mainface]}, after=\stopformula ] \starttext abcdefg ABCDEFG 123456 i \startformula {\tf abcdefg\,ABCDEFG} \quad abcdefg\,ABCDEFG \quad 123456 \quad {\bf 123456} \stopformula % it works: \startformula Y=X\beta+\varepsilon \stopformula % it works: \startformulass Y=X\beta+\varepsilon \stopformulass % it doesn't work: \startformulass \startalign[n=4] \NC Y_t \NC = \beta_0 \NC + \beta_1 x_t \NC + \varepsilon_t \NR \NC Y_t \NC = \beta_0 \NC + \beta_1 x_t \NC + \varepsilon_t \NR \stopalign \stopformulass \stoptext %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% Could you please give me some advices? Thanks in advance! -- «...my role is to be on the bottom of things.» Donald Knuth