Dear Board, It's going to take some work to come up with a test file for this problem (since the font is not publically available), but let me describe it anyway: Arabic visually requires larger font sizes than roman, as well as wider interline spacing, so Arabic insertions in Latin can create lines of mixed interline spacing. Very strangely, this problem is more apparent in itemize environments and the like than in regular text. Question: is there a way to turn off interline spacing completely for my insertions when necessary. Insertions are defined in terms of \startarabictext \stoparabictext environments: \definestartstop [arabictext] [commands=% {\osetarabdirtext % switches to RL mode \arabictextfont % switches to Arabic \vocalizeinsertdefault} % calls default otp list for vocalization ] Idris