I don't seem quite able to put it all together, forgive the question. I have a 'Bookman' font setup, pretty vanilla: \definetypeface [Bookman] [rm] [serif] [bonum] [sl=name:unituscndboldoblique] \definetypeface [Bookman] [tt] [mono] [modern] [default] \definetypeface [Bookman] [ss] [sans] [unitus] [default] \definetypeface [Bookman] [mm] [math] [modern] [default] (Unitus is the fontsite 500 'Univers' substitute, works fine) Now, the built-in gyre bonum font doesn't have a slanted/oblique variant, so if I have Bookman as my main body font, \sl produces (unsurprisingly) the same result as \it, TexGyreBonum-Italic. If I want \sl to summon Latin Modern for the variant, I have tried variations on \definetypeface [Bookman] [rm] [serif] [bonum] [sl=file:Latin Modern Roman Slanted] but to no avail — not helped by the fact that the \definetypeface contextgarden page doesn't have any pointer to just what that fifth argument can contain. How do I accomplish this?