Any ideas?
This is a catcode problem. Surround \start ... \stoplilypond with \catcode`\-=11 and \catcode`\-=12 Then you will probably experience a Lilypond problem because the line of code you type (\markup \fret-diagram ...) apparently isn't a legitimate Lilypond stand-alone score and you need to place it on the page with \mark, for example. But even then Lilypond is not so happy and complains that there is no note on the page, and you'd better put some there. To sum up, the following works for me: ---- cut after \usemodule[lilypond] \starttext \catcode`\-=11 \startlilypond d'' ^ \markup { \fret-diagram #"s:0.75;6-x;5-x;4-o;3-2;2-3;1-2;" } \stoplilypond \catcode`\-=12 \stoptext ---- cut before Have fun! Note for Hraban: this problem is apparently special to markups, that somehow the minus signs loses his letterhood when used in a markup. The fault lies obviously with Lilypond, since when I try to compile the following exact line (with the added curly braces): { \markup \fret-diagram #"s:0.75;f:1;6-x;5-x;4-o;3-2-1;2-3-3;1-2-2;" } Lilypond seems to suddenly forget that the minus is part of the command and complains about an “unknown escaped string: `\fret'”. I have no idea what to do in t-lilypond to fix it. Maybe you know? Arthur