Hi, As I am moving from mkII to mkIV with my thesis manuscript, I need to make the 'left||right synchronization mechanism' to work. I worked beautifully in mkII. I looked in the source of the module but could not make out where the issue is. I errors I get today begin like this. (/home/me/context/tex/texmf-context/tex/context/base/m-streams.tex ! Undefined control sequence. l.19 \defineoutputstream [\v!left] ? ! Undefined control sequence. l.20 \defineoutputstream [\v!right] ? ! Undefined control sequence. l.22 \definemarknote [\v!left] ? ! Undefined control sequence. l.23 \definemarknote [\v!right] ? ) system : module streams loaded ___________________________________________________ what is this ( \v! ) thing? where can I get the clues? Does it come from Tex or LuaTex programming? Thanks, Salil