Hi, the vertical line symbol "|" (pipe) breaks \processaction (no problem with the latest stable version). The minimal example at the end of this message results in: [..] systems : begin file processaction at line 3 ! Undefined control sequence. \dotextmodediscretionary ...up \let \nextnextnext \egroup \def \next ##1#1{\... \p!compareprocessaction ...]->\edef \!!stringb {#1 }\ifx \!!stringb \s!defaul... \next1 #1,->\p!doprocessaction {#1} \doprocesscommaitem <argument> =>, unknown=> \processnextcommalist ...dodoprocesscommaitem #4#5 ,]\relax \global \advance ... l.9 unknown=>] ? Greetings, Peter ----- \setupoutput[pdftex] \starttext \def\FOO{} \processaction[\FOO][ |=>, unknown=>] \stoptext